Correct option: (A, D)
Explanation:
Suppose n loops are formed in wire AC and m loops are formed in wire BC
So the loops in wires AC should be n = 2, 4, 6 .......
So the loops in wires BC should be m = 5, 10, 15 .......
Fundamental frequencies of wire AC as well as BC are :
f = 100 Hz, 200 Hz, 300 Hz ........