- A total of 17 volunteers are involved in the TR project and 10 in TR are also involved in other projects. Thus, 7 volunteers are involved only in TR.
- The number of volunteers involved in the TR project alone is one less than the number of volunteers involved in the ER project alone. Eight volunteers are involved in ER alone.
- The number of volunteers involved in the ER project alone is double the number of volunteers involved in all the three projects. So, 4 volunteers are involved in all the three projects.
- Among them, the number of volunteers involved in the FR project alone is equal to the number of volunteers having involvement in the ER project alone. So, 8 volunteers are involved in FR alone.
- Let number of volunteers involved in both TR and FR but not ER = a
Number of volunteers involved in both TR and ER but not FR = b
a + b + 4 = 10
a + b = 6
Let number of volunteers involved in both FR and ER but not TR = x
Total = 17 + x + 8 + 8 = 37
x = 4
Consider the Venn diagram shown below:

Number of volunteers involved in FR > Number of volunteers involved in ER
16 + a > 16 + b
a and b can be (6, 0), (5, 1), or (4, 2).
After the volunteers withdraw as mentioned, the number of volunteers working on different projects is as shown below:

After the volunteers withdraw as mentioned,
- Number of volunteers working on TR = 7 + 6 + 3 = 16
- Number of volunteers working on FR = 14 + a
- Number of volunteers working on ER = 15 + b
From options:
1. The lowest number of volunteers is now in the TR project.
Incorrect: For b = 0, Number of volunteers working on ER = 15
2. More volunteers are now in the ER project as compared to the TR project.
Incorrect: For b = 0, Number of volunteers working on ER = 15
3. More volunteers are now in the TR project as compared to the ER project.
Incorrect: For b = 2, Number of volunteers working on ER = 17
4. More volunteers are now in the FR project as compared to the ER project.
Correct for all possible value of a and b: 14 + a > 15 + b
(a, b) = (6, 0), (5, 1), (4, 2)
∴ More volunteers are now in FR than in ER.
Therefore, option 4 is the correct answer.