Final answer:
Flow states are most likely to occur when engaging in a challenging, yet compelling activity that matches one's skill level. Correct option is b.
Step-by-step explanation:
A flow state is typically experienced when engaging in a challenging, yet compelling activity. It occurs when the level of challenge in the activity matches the individual's skill level, leading to a sense of deep focus, enjoyment, and fulfillment. Daydreaming about the future, being paid at a job, or engaging in sexual activity may not necessarily induce a flow state, as they do not involve the same level of challenge and skill required for flow.