Talk to your school or your boss at work possibly
Answer: (7) It appears that tremendous numbers of consumers are influenced by advertising, despite their claims to the contrary.
Explanation:
The main idea of this passage is that advertising works despite people's claims to the contrary.
This is the main idea because every other sentence centres around this one with the first sentence attempting to explain how it works.
The second sentence then attempts to disprove it while the third, fourth, fifth and the sixth show show evidence of its truthfulness.