(A) One should pay for any damage that one’s action leads other people to cause if one could have reasonably expected that the action would lead other people to cause damage.
Correct. The conclusion states that if someone could have reasonably expected an action they should be liable for the damages that they cause. (A) has to be assumed for the conclusion to work.
(B) One should pay for damage that one’s action leads other people to cause only if, prior to the action, one expected that the action would lead other people to cause that damage.
"only" is a limiter. The conclusion could still be inferred if there are other reasons to pay damages alongside the one given.
(C) It is unlikely that the people who trespassed on and caused the damage to the Mendels’ property would themselves pay for the damage they caused.
Unrelated to the conclusion.
(D) Ms. Sandstrom knew that her column could incite trespassing that could result in damage to the Mendels’ farm.
Unrelated to the conclusion.
(E) The Mendels believe that Ms. Sandstrom is able to form reasonable expectations about the consequences of her actions.
Again this doesn't need to be true. The conclusion of the paragraph is already asserting that Ms. Sandstrom should pay IF she can form a reasonable expectation about the damages that were done, and it is not asserting that she should necessarily pay for it because she DOES have this ability.
IMO A