Final answer:
The compound inequality that represents the situation is 10 < x < 65.
Step-by-step explanation:
The compound inequality that represents the situation is a) 10 < x < 65. This means that the variable x represents the finishing time of the participants in the 5K race, and the inequality indicates that the finishing time must be greater than 10 minutes and less than 65 minutes. Option a) is the correct answer because it represents the range of possible values for x in the given context.