[单选题]
An object in simple harmonic motion obeys thle1xwf:nwj.u, riqd6k1 v0 )ne following position versus time;xjqqv+am7s81 3vq h h equatiohq ;j1 smvq8a+q7 v3hxn: $y = 0.50 \; \sin (\pi/2 \times t)$. What is the period of vibration?
A. $1.0 \; s$
B. $2.0 \; s$
C. $3.0 \; s$
D. $4.0 \; s$
