Understanding the argument -
The government will purchase and install new severe weather sirens for this area next year if replacement parts for the old sirens are difficult to obtain. - if conditional.
The newspaper claims that public safety in the event of severe weather would be enhanced if new sirens were to be installed. -
Lets understand this sufficient condition as its critical to eliminate option A.
This option says, if new sirens were to be installed, the public safety would be enhanced.
It means that "new sirens" is a sufficient condition for "enhanced public safety." Meaning, if you install new sirens, there is a 100% guarantee that the public safety would be enhanced.
Does it say that "only new sirens" can increase the public safety? No. It can be increased by say 20 other factors. So, "new sirens" is a sufficient condition and not the only condition.
The local company from which replacement parts were purchased last year has since gone out of business. - Fact
So, if the newspaper is correct, the public will be safer during severe weather in the future. - Conclusion.
The argument’s conclusion follows logically from its premises if which one of the following is assumed?
(A) If public safety in the event of severe weather is enhanced next year, it will be because new sirens have been purchased. - Do we need to assume that "new sirens" is the only condition? No.
(B) The newspaper was correct in claiming that public safety in the event of severe weather would be enhanced if new sirens were purchased. - the argument already says "assuming its correct." Assumption is a missing premise and not stating the same information as presented in the argument.
(C) The local company from which replacement parts for the old sirens were purchased last year was the only company in the area that sold them. - this is not an assumption as there could be 20 other companies outside the area. There is nothing in the argument that necessities that we need to buy only from the area. Wrong.
(D) Replacement parts for the old sirens will be difficult to obtain if the government cannot obtain them from the company it purchased them from last year. - ok.
(E) Because the local company from which replacement parts had been purchased went out of business, the only available parts are of such inferior quality that use of them would make the sirens less reliable. - "inferior quality" is out of scope of the argument.