A salesperson should ask a prospect to buy a product only when the prospect reaches the ________ stage of the mental buying process.

A) knowledge
B) attitude
C) conviction
D) belief
E) desire

The correct stage is "conviction." This is when the prospect is convinced about the value and benefits of the product, making it the most appropriate time for a salesperson to ask for the purchase. Conviction indicates that the prospect has moved beyond mere interest or belief and is now convinced that the product meets their needs, making them more likely to buy.