A.I. Explanation:

Option 1: "Intrinsic motivation is more common than extrinsic motivation."

Explanation: This option incorrectly asserts a comparison between intrinsic and extrinsic motivation, which is not discussed in the text. The text focuses on the effects of extrinsic motivation on intrinsic motivation rather than their prevalence.

Option 2: "People are motivated to work harder for two different kinds of reasons."

Explanation: While this option mentions two types of motivation, it does not capture the specific relationship between extrinsic and intrinsic motivation as described in the text. The text emphasizes the unexpected effects of extrinsic motivation on intrinsic motivation, not just the existence of two types.

Option 3: "There may be surprising effects of extrinsic motivation on intrinsic motivation."

Explanation: This option accurately paraphrases the main idea of the text, which discusses how extrinsic motivation can unexpectedly influence intrinsic motivation. The use of 'surprising effects' aligns with the examples provided in the text, where rewards and punishments led to unexpected outcomes in children's interest.

Option 4: "Children work better when they are offered something nice in the end."

Explanation: This option misrepresents the text by suggesting that offering rewards always leads to better performance. The text indicates that offering rewards can actually decrease intrinsic motivation, which contradicts the implication that rewards are always beneficial.