A behavioral psychologist interested in animal behavior noticed that

Claims:
dogs who are never physically disciplined (e.g., with a blow from a rolled-up newspaper) never bark at strangers

Assumption:
Since, dogs must bark at strangers in ought to alert the owner.
So,What makes a dog bark at strangers?

Conclusion:
No physical punishment = keep from barking

1) The psychologist’s conclusion is based on which of the following assumptions?

A. Striking a dog with a newspaper or other object is an inappropriate method for conditioning canine behavior.
Striking itself is a punishment. Negates the conclusion
B. Dogs that are never physically disciplined grow up more well-adjusted than dogs that have been subjected to such discipline.
Compares dogs with their nature. But,who barks more and who barks less? Out of way
C. There were no instances of an unpunished dog barking at a stranger that had not been observed.
no instances of unpunished dog barking = there may be instances of punished dog barking (w.r.t author's notice)
So assuming that dogs are not punished then they will not bark. Assumption fits
D. Dogs normally bark only at strangers who have previously been physically abortive or threatening.
Conditional. past doesn't necessarily be same as present
E. Human children who are physically disciplined are more likely to react negatively to strangers than those who are not.
Human Children? Irrelevant

2)Suppose the psychologist decides to pursue her project further, and she studies 25 dogs that are known to bark at strangers. Which of the following possible findings would undermine her original conclusion?

Conclusion:
No physical punishment = Keep dogs from barking atstrangers

(Study is on dogs that are known to bark.
So findings should talk about physical punishment and negate the conclusion)

A. Some of the owners of the dogs studied did not physically punish the dog when it barked at a stranger.
Statement says (No physical punishment and barked). Talks about Physical punishment but Conditional.
Some of the dogs were not physically punished.It means 2 dogs can get the punishment or may be 10 dogs get the punishment. But all dogs are known to bark
B. Some of the dogs studied were never physically punished.
Statement says Few punished, few are not, but still all the dogs are known to bark. Doesn't support the conclusion
C. The owners of some of the dogs studied believe that a dog which barks at strangers is a good watchdog.
Irrelevant. Because, it's not about the good dog or bad dog
D. Some of the dogs barked at people who were not strangers.
Doesn't talk about physical punishment. Conditional.
E. None of the dogs was disciplined by the method of a rolled-up newspaper.
Talks about the punishment method (from author's example: dogs who are never physically disciplined (e.g., with a blow from a rolled-up newspaper never bark at strangers). None of the dogs was disciplined, but the study is on dogs which are known to bark.
This inference violates the conclusion.

Answers: C and E