Study the following table and answer the question given below it.
The given table represents the marks obtained by four students W. X, Y and Z in four Subjects P, C, B and M, with the maximum marks in each subject being 100.
| Stu/Sub | P | C | B | M |
| W | 70 | 90 | 50 | 85 |
| X | 55 | 80 | 95 | 60 |
| Y | 60 | 20 | 90 | 40 |
| Z | 90 | 80 | 40 | 65 |
What is the difference between the average marks of four students in P and the average marks of four students in M?
1
5.75
2
6.75
3
6.25
4
7.20