大全里没问过的C－15，帮忙解释一下！

15.   Bill: Smoke-detecting fire alarms can save lives. I believe that every apartment in this city should be required by law to be equipped with a smoke detector.

Joe: I disagree with your proposal. Smoke detectors are just as important for safety in private houses as they are in apartment.

From this exchange, it can be inferred that Joe has interpreted Bill’s statement to mean that

(A) the city should be responsible for providing smoke detectors for apartments

(B) residences outside the city should not be equipped with smoke detectors

(C) only apartments should be equipped with smoke detectors

(D) the risk of fire is not as great in private houses as it is in apartments（C）
(E) the rate of death by fire is unusually high in the city in question

为什么会是C呀？帮忙解释解释。谢谢。

B说，因为SD可以救命，所以每个apartment都该装

J说：不同意。因为sd在私人house和apartment对于安全一样重要

问：J误解了B什么

C：J误以为B只想在apartment里面装SD