Trial and Error technique:
Trial 1:
Let p=2, q=3
Therefore, n=12
Conditions to be satisfied:
1<=m<=12
gcd(m,12)=1
Therefore, m could be => 1,5,7,9 => 4 values
Choices A & D satisfy
Trial 2:
Let p=3, q=2
Therefore, n=18
Conditions to be satisfied:
1<=m<=18
gcd(m,18)=1
Therefore, m could be => 1,5,7,11,13,17 => 6 values
Choice A not satisfied, Choice D satisfied. Therefore, D.