Final answer:
The measure by which it is determined whether an ad causes a false belief is if it contains any factually incorrect information.
Step-by-step explanation:
The measure by which it is determined whether an ad causes a false belief is if it contains any factually incorrect information. Advertisers are allowed to use language and images that are exaggerated or ambiguous but not actually false. However, if a claim is presented as a fact, it must be true according to the government rules on advertising enforced by the Federal Trade Commission (FTC).
For example, if an ad claims that a certain product can cure a disease, but it is not supported by scientific evidence, then it can be considered factually incorrect. Additionally, if an ad makes false claims about a product's performance or attributes, it can also be deemed as causing a false belief.