A is contradicted by the passage. If buyers will readily accept other spices, that means the spices dont matter much to them and the ratings would all be teh same. The passage states that the ratings are very different, meaning some spices are unacceptable and others are acceptable.
My choice is C too.
Casseroles differ in type of spice .
Assumption:One of the spice(say X) is popular and the casserole which contains X received highest ratings.
Inference:Casserole with X sells better.
A weakens the above logic.