Support or contrast?

After a slow sales start early in the year, mobile homes have been gaining favor as ________ to increasingly expensive conventional housing.

(A) reaction (B) an addition (C) an introduction (D) an alternative (E) a challenge

Can someone help me figure out what is the SUPPORT or CONTRAST word that will help us answer this question? I choose (D) - an alternate because that seemed the most fit but how to do this with math strategy ?

It is a time contrast. You can see “After” a slow sales start early in the year, which means later in the year the sales for mobile homes boomed or increased compared to conventional housing or it was an alternate option
Out of the options you can eliminate reaction and introduction as it has no evidence. Addition can make sense but we have the evidence gaining favour so we have to chose an option that prioritizes mobile homes as addition indicates both exist. So we can eliminate it. Challenge has a contrasting evidence so it is eliminated. So the only one we can choose is D (an alternative)
@gregmat pls correct if I am wrong