[单选题]
An object in simple hayxnjj 4a736 mqmxh6 *ftag9yjak7 :q4 rmonic mot l78dyeo q xtwp*dn s(k/(88faion obeys the following position versus time equatiod/xe akn8wqol t 8fd s87*p((yn: $y = 0.50 \; \sin (\pi/2 \times t)$. What is the period of vibration?
A. $1.0 \; s$
B. $2.0 \; s$
C. $3.0 \; s$
D. $4.0 \; s$