To solve this question, the user needs to know that the frog can jump 3 feet but falls back 2 feet every time he jumps. The user should calculate how many jumps the frog needs to make to get out of the well.

Let's go through each option and explain why it is right or wrong:

A. 9: This option is incorrect. If the frog jumps 9 times, he will reach a height of 27 feet, which is higher than the well itself. Therefore, the frog will escape the well before he makes his 9th jump.

B. 8: This option is correct. If the frog jumps 8 times, he will reach a height of 24 feet. On his 8th jump, he will reach the top of the well and will no longer fall back 2 feet.

C. 10: This option is incorrect. If the frog jumps 10 times, he will reach a height of 30 feet, which is higher than the well itself. Therefore, the frog will escape the well before he makes his 10th jump.

D. 7: This option is incorrect. If the frog jumps 7 times, he will reach a height of 21 feet. On his 7th jump, he will reach a height of 21 feet, then he will fall back 2 feet, which means he will be at a height of 19 feet. Therefore, the frog will need to make at least one more jump to escape the well.

The Answer is: B. 8