Explanation:

- There are six persons: P, Q, R, S, T, and U.

- They were born in May, September, and November, on the dates 9 and 16.

- P was born after R, but not on the same date.

- S has an equal number of people born before and after him, implying S is in the middle.

- Q and U were born in the same month.

- T was born in a month with 30 days, so T was born in September.

- Two people were born between R and T.

From this information, we can deduce:

1. R is born on May 9.

2. T is born on September 9.

3. P is born on November 9.

4. S is born on September 16.

5. Q and U are both born in November on 16.

- R is the first person on the list and no one is immediately before R.

Thus, the correct answer is option: 5, No one.