I insufficient
n/3 rem 2 2,5,8,11,14,17,20
II insufficient
n/5 rem 3 3,8,13,18,23
1) N=2,7,12,17............
2) 2)t=3,6,9,12,15,18.............
1 n 2 combined
N 2,17,32..
T 3,18....
Nt 6,51,36,96 divide them by 15 the remainder is alwaz 6
So C