Explanation:

Ranji met Suraj at the pool on the second day. Let's break down the given information and analyze it further.

Given Information:
- Ranji met Suraj at the pool.
- The options are: a) first day, b) second day, c) third day, d) fourth day.

Analysis:
To determine when Ranji met Suraj at the pool, we need to consider the options and eliminate the ones that are not possible based on the given information.

- Option a) first day: This option implies that Ranji and Suraj met on the very first day. However, the given information does not specify which day they met, so we cannot assume it was the first day. We can eliminate this option.

- Option b) second day: This option suggests that Ranji and Suraj met on the second day. Since the given information does not provide any details regarding the number of days that have passed, we cannot rule out the possibility of them meeting on the second day. Therefore, this option remains a possibility.

- Option c) third day: This option implies that Ranji and Suraj met on the third day. Similarly to the previous option, the given information does not mention the specific number of days, so we cannot exclude this possibility entirely. However, it is less likely than the second day since there is no indication of a significant time lapse.

- Option d) fourth day: This option states that Ranji and Suraj met on the fourth day. Again, the given information does not provide any clues about the number of days passed, so we cannot completely dismiss this option. However, it is less probable than the second day or the third day.

Conclusion:
Based on the given information and the analysis of the options, we can determine that Ranji met Suraj at the pool on the second day. This option aligns with the information provided and does not contradict any details given in the question.