B

@candace, Happy to help. (B) says, "Most of the products purchased in response to direct-mail advertisements would be purchased even without the direct-mail advertisements." If people are buying items that they would be purchasing even without the direct-mail advertisements, then the fact that direct-mail advertisements would save these people trips to the store (causing them to use less gasoline) is a relevant detail. Thus, (B) strengthens the argument. Does this make sense? Let us know if you have any other questions!

@Ravi how can we assume that these items, which people were planning on purchasing anyway, would have required a trip to the store? I don't see how this answer suggest a change in consumption patterns in a way that necessarily is more environmentally-friendly.

Hello @Hannah-Anderson, According to the passage, we are talking specifically about products "whose purchase would otherwise require the use of a car." We don't have to assume that these products require a trip to the store, because that information is already given to us.