[单选题]
An object in simple harmfv4xt5iy5c3t a/*h ivod w3)+p*(4wg n 2v voq4qfcmdenic motion obeys the following position versus time equamv3)qw 4qpddgeo*2vncf ( +4w tion: $y = 0.50 \; \sin (\pi/2 \times t)$. What is the amplitude of vibration?
A. $0.25 \; m$
B. $0.50 \; m$
C. $0.75 \; m$
D. $1.0 \; m$
