(A) only has one necessary condition: good weather. (A) just concludes that since the army has good weather, it will meet its objectives. This is incorrect (because we don’t know that good weather is a sufficient condition as well as a necessary condition) but it makes a different error from the argument in the stimulus.

(B) lays out a sufficient condition for being in Chicago or Toronto, and concludes that since the sufficient condition isn’t fulfilled, Louis isn’t in either of the two places. This is an invalid argument, but doesn’t make the “exclusive or” error.

(C) says that since a necessary condition (Horan and Jacobs not entering) is true, the conclusion (Johnson will win) is also true. The error here is confusing sufficient and necessary, but (C) doesn’t make the “exclusive or” mistake.

(D) states that to be informed about current events, one must fulfill condition A (read a major newspaper) or condition B (watch TV news) — and concludes that since Julie is informed and fulfills condition A, Julie does not fulfill condition B. This is the same reasoning as in the stimulus, and makes the same error: assuming that “or” is exclusive.

(E) says that to get a ride home, condition A (Yvette being there) or condition B (Marty being there) is necessary. But (E) concludes that since condition A isn’t true, condition B must be. This is different from the stimulus, which concludes that since one condition is true, the other must not be.