A) 60%
C) 80%
B) 70%
D) None of these
Total marks of 3 subject = 75 + 80 + 85 = 240 out of 300 at least average marks ≥ 240 out of 400.
Considering worst case possibility, mark of fourth subject = 0
Average of marks ≥ (240/400) × 100 = 60%
∴ Average will always be more than 60%.