[单选题]
An object in simple haruuzp++v8 jbx; 1ws crb.l;( okmonic mot rz3 sxsx7vo8d0a jj:+-t z/biion obeys the following position versus time equatidsxt-xs obraj/8 :7z iv+zj 30on: $y = 0.50 \; \sin (\pi/2 \times t)$. What is the period of vibration?
A. $1.0 \; s$
B. $2.0 \; s$
C. $3.0 \; s$
D. $4.0 \; s$
