Power Electronics - Engineering

Q1:

In the below figure, the load is highly inductive. The firing angle is a for each of the thyristors. The periods of conduction of Th1 and Th2 respectively are

A
0 to p and p to 2p

B
a to p and p + a to 2p

C
a to p + a and p + p to 2p + a

D
a to p - a and p + a to 2p - a

ANS:C -

a to p + a and p + p to 2p + a

Can somebody please explain this problem in detail?