In Bait and Switch Legal Cases, the Most Difficult Test

In bait and switch legal cases, the most difficult test of a bait and switch tactic to prove is that

A) the retailer intentionally did not stock enough of a sale item with the intent of running out, thus causing customers to switch to a higher-priced model
B) salespeople used undue pressure to influence customers to purchase a higher-priced model
C) the advertisement used deceptive and misleading information
D) the salespeople made false claims about the advertised model