Dave's ESL Cafe's Student Discussion Forums

[www0935]

The following is my question:

We take it for granted that a product is probably not as good as the manufacturers claim, __________ the detergent does not take out every dirty spot instantly without a lot of hard work－or at least not as quickly as the TV commercial shows.
(A) that (B) so as (C) or (D) since

This answer is (A), but I think (D) is better. Could someone help me out?
Thanks a lot.

[pugachevV]

That is correct here. It is simply introducing a subordinate clause, which is backing up the initial general assertion that manufacturers lie about their products with a specific instance.