Which of the following is a common technique advertisers use to mislead consumers into using "fad diets"ť to achieve optimal health and fitness?

The common technique advertisers use is that they advertise products that promote quick weight loss by having an unhealthy and unbalanced diet which is called the Fad diet. Advertisers seem to promote a good to be true products which then can lead to someone to follow the diet well, in fact, it can be of at risk for serious illnesses such as liver or renal diseases. so the correct option is

C. Allowing only one or two food types is common technique advertisers use to mislead consumers into using "fad diets" to achieve optimal health and fitness.

Explanation:
Fad diet could be a diet that guarantees fast weight loss through what's typically associate degree unhealthy and unbalanced diet. Cult diets are targeted at those that need to thin quickly while not exercise. Cult diets that are restricted to bound foods may match, however, most are boring or unappealing.

Target heart rate is the answer