Chapter 13 - Vibrations and Waves - Learning Path Questions and Exercises - Multiple Choice Questions - Page 483: 7

(b) $-A$

One complete cycle of simple harmonic motion can be divided into four quarters. In first quarter, the object moves from y=0 to y=+A, In second quarter, it moves from y=+A to y=0, In third quarter, it moves from y=0 to y=-A, In fourth quarter, it moves from y=-A to y=0. So, after three quarter, the position is y=-A.