(A): This answer choice is incorrect because the conclusion does not require that the scientists who submitted manipulated images were aware that the journal was using the software described in the stimulus. To the contrary, evidence that the scientists knew the photographs would be analyzed may weaken the conclusion that they were attempting to commit scientific fraud.

(B): This answer choice explains why scientists submit digital images with their articles. However, it does not connect the violation of the journal’s guidelines with scientific fraud.

(C): Here, the answer choice is incorrect because it is unnecessarily restrictive. While the stimulus did discuss scientific fraud in cellular biology, we cannot say that the documentation with digital images is the only way to commit scientific fraud in the field of cellular biology.

(D): This is the correct answer choice. The premises only speak about digital image manipulations. The concluding sentence 'Clearly, scientific fraud is a widespread problem among the authors submitting to that journal.' suddenly brings up fraud into the equation. In order to conclude that fraud is committed, the assumption is that there an intention to misrepresent. This option states that exact assumption.

(E): As with (C), this answer is too restrictive. It does not have to be the case that widespread fraud is only a problem relating to articles submitted to journals of cellular biology.

Among the many temptations of the digital age, manipulation of photographs has proved particularly troublesome for science. Recently, a journal of cellular biology began using a software tool to examine the digital images submitted along with articles for publication. It discovered that dozens of authors had submitted digital images that had been manipulated in ways that violated the journal's guidelines. Clearly, scientific fraud is a widespread problem among the authors submitting to that journal.

Which one of the following is an assumption required by the argument?

(A) The scientists who submitted manjpulated images were aware that the journal used software to examine digital images for evidence of manipulation.
Even if the scientists knew about the software it doesn't tell us whether the scientists were fraud.

(B) The journal requires that all articles submitted for publication include digital images.
Requirement is not the required assumption

(C) Scientific fraud is possible in the field of cellular biology only if the research is documented with digital images.
Only if --this makes the option exaggerated

(D) Many of the scientists who submitted articles with manipulated images did so in order to misrepresent the information conveyed by those images.
Correct. If the scientists had fraudulent intentions then it closes the gap in the argument

(E) Scientific fraud is a widespread problem only among scientists who submit articles to journals of cellular biology.
We are worried about the particular journal and not all the journals in general

(A) The scientists who submitted manjpulated images were aware that the journal used software to examine digital images for evidence of manipulation. Negated statement stregthens the conclusion & hence not an assumption
(B) The journal requires that all articles submitted for publication include digital images. "All" is an issue. What if if it is not all.
(C) Scientific fraud is possible in the field of cellular biology only if the research is documented with digital images. only is an issue
(D) Many of the scientists who submitted articles with manipulated images did so in order to misrepresent the information conveyed by those images. Keep it. Discusses a new info & negation breaks the conclusion
(E) Scientific fraud is a widespread problem only among scientists who submit articles to journals of cellular biology. only is issue

A. Verification doesn’t prove anything one way or another. The scientists might have intended fraud even if they knew there were verifications, thinking they wouldn’t get
caught.

B. This doesn’t tell us whether the images were submitted with fraud in mind. Requiring an image doesn’t make an honest person fraudulent or a fraudulent person honest.

C. The negation of this doesn’t affect the argument.
Negation: Fraud can happen whether or not research has images.

D.CORRECT. Fraud requires intent. If you negate this then few scientists intended to commit fraud when they manipulated images. Remember, the conclusion is that fraud is a widespread problem.
Negation: Not many (i.e. few to zero) scientists manipulated images with fraudulent intent.

E. This is not necessary.
Negation: Widespread scientific fraud is possible in many fields, not just cellular biology.

I do not agree with the official answer, nor I can see any answer to be better than others.

Here is why:
The passage states that
In order for the fraud to be "widespread", some of the authors has to submit faulty digital images.

Official answer states, that ; the OA, however, doesn't tell you how many such scientists are there.

The OA to be true, we expect that number of fraudulent submissions must a significant part of total submissions.

But, for example,
There were 100,000 articles submitted.
Out of them 100 had digital images.
Out of 100, 60 ("dozens" per text) were with frauds. (to comply with official answer that "many" with frauds).
So it makes 60/100000 = 0.06% - is it widespread? In common sense, and in my sense as well, it is not widespread at all! Therefore I consider OA to be not correct and the question to be of a poor quality.

Please correct me, if i'm wrong.
Thank you!

Option D is a 'Must be true' in this case, hence correct choice.

My two cents on the explanation of the argument
Manipulation of photographs has proved particularly troublesome for science, they have recently discovered that dozens of authors had submitted images that had been manipulated and from here the author jumps to mention that fraud is a widespread problem, basically as per the author manipulation = fraud. Let's look at the option choices now

(A) The scientists who submitted manipulated images were aware that the journal used software to examine digital images for evidence of manipulation This has no bearing on the argument, so eliminate this one, and if the scientists were committing fraud then knowing about a software tool which is used for evaluation, they would have done other fraudulent activities, This option in its current states is actig as a weakner, so this is out(remember the correct answer to assumption should act as a weakener once it is negated)

(B) The journal requires that all articles submitted for publication include digital images. Not related to the argument

(C) Scientific fraud is possible in the field of cellular biology only if the research is documented with digital images. This need not be true for the argument

(D) Many of the scientists who submitted articles with manipulated images did so in order to misrepresent the information conveyed by those images. For better or good, this is the one we are stuck with, if we negate this, we see it weakens the argument, hence this is the correct answer choice

(E) Scientific fraud is a widespread problem only among scientists who submit articles to journals of cellular biology Again, this need not be true, it could be, but not required

We don't know anything about the sample size, also forgive me for my hazy memory but I remember reading it somewhere (may be in PowerScope) that the author always assumes his argument to be air tight, so don't try to find issues in the argument, we are asked to find the assumption not flaw in reasoning.

Hope this helps