Variation of efficacy is the phrase that is questionable in the context of advertising.
What are advertising and promotion guidelines?
According to FDA, there are a set of instructions and rules in the form of guidelines that the product manufacturer should be aware of before the product is released into the market.
- Breakthrough advertising does not violate any rules and it cannot be questionable, because through this process the company or the maufacturer is only truying to gain the attention of the target group or the audience.
- According to PHS act, labelling as FDA appoved product is accepted.
- Products that have undergone strict clinical trials are only termed as medically approved an it cannot be a questionable content.
Hence, option D is the right answer.
To learn more about FDA and its regulations, refer:
https://brainly.com/question/6669779
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