Final answer:
Studying for a test to earn a good grade is an example of extrinsic motivation.
Step-by-step explanation:
The most likely example of extrinsic motivation among the given options is 1) Studying for a test to earn a good grade. Extrinsic motivation refers to engaging in a behavior for external rewards or consequences. In this case, the student is studying to earn a good grade, which is an external reward. The other options are examples of intrinsic motivation, where the behavior is performed for personal enjoyment or satisfaction.