Advertisers are often criticized for their unscrupulous manipulation of people’s tastes and wants.
Conclusion
Some advertisers are motivated by moral as well as financial considerations.
Evidence
A publication switched from being a family newspaper to focusing on sex and violence. Some advertisers withdrew their ads. The author concludes this withdrawal "must have been because" they morally disapproved of the new content.
Evaluate
The author leaps from the fact of withdrawal to the cause: morality. But there is an obvious alternative — the advertisers might have withdrawn because the new content would not sell to their customers, which is a financial reason. To support a moral motive, we need to rule out the financial-self-interest explanation.
Goal
The correct answer should make it harder to attribute the withdrawal to financial self-interest — for instance, by showing the advertisers expected staying to be more profitable.