Each of B, Q, C, N, X, U and M has an exam on a different day of a week, starting from Monday and ending on Sunday of the same week. Only two people have exams before Q. Only one person has the exam after N. B has the exam before U but after Q. X has the exam immediately before C. M does not have the exam before U.

How many people have exams between U and X?

The correct option is Three.

Let's determine the schedule of the exams for each person step-by-step based on the given information. The week starts on Monday and ends on Sunday, giving us seven days: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, and Sunday.

1. "Only two people have exams before Q."
This means Q's exam must be on the third day of the week, which is Wednesday.
Schedule so far:
- Monday:
- Tuesday:
- Wednesday: Q
- Thursday:
- Friday:
- Saturday:
- Sunday:

2. "Only one person has the exam after N."
This means N's exam must be on the second-to-last day of the week, which is Saturday.
Schedule so far:
- Monday:
- Tuesday:
- Wednesday: Q
- Thursday:
- Friday:
- Saturday: N
- Sunday:

3. "B has the exam before U but after Q."
Since Q has their exam on Wednesday, B must have their exam after Wednesday. Also, U has their exam after B. This means B and U must occupy two of the remaining slots after Wednesday (Thursday, Friday, or Sunday; since Saturday is N). Since B is before U, the possible days for B and U are either Thursday and Friday, Thursday and Sunday, or Friday and Sunday.

4. "X has the exam immediately before C."
This requires two consecutive vacant days. Looking at our schedule, the only consecutive vacant days remaining are Monday and Tuesday. Therefore, X must have the exam on Monday, and C must have the exam on Tuesday.
Schedule so far:
- Monday: X
- Tuesday: C
- Wednesday: Q
- Thursday:
- Friday:
- Saturday: N
- Sunday:

5. "B has the exam before U but after Q" and "M does not have the exam before U."
The remaining empty slots are Thursday, Friday, and Sunday. The remaining people to place are B, U, and M.
Since B must be after Q (Wednesday) and before U, and M does not have the exam before U (meaning M has the exam after U), the order must be B, then U, and then M.
Thus, the remaining slots are filled as:
- Thursday: B
- Friday: U
- Sunday: M

The complete schedule is:
- Monday: X
- Tuesday: C
- Wednesday: Q
- Thursday: B
- Friday: U
- Saturday: N
- Sunday: M

6. Count the number of people between U and X:
- X has the exam on Monday.
- U has the exam on Friday.
- The people with exams between Monday (X) and Friday (U) are C (Tuesday), Q (Wednesday), and B (Thursday).
There are exactly 3 people (C, Q, and B) who have exams between U and X.