While measuring the distance between two points along upgrade with the help of a 20 m chain, the forward end of the chain is shifted forward through a distance_____.

A)
20 (cos θ - 1)
B)
20 (sin θ - 1)
C)
20 (sec θ - 1)
D)
20 (cosec θ - 1)

Correct Answer :   20 (sec θ - 1)