[单选题]
An object in simple harmonic motnh2 z,bx-/m*knm)cpk io8.*1jtctna 7f 71zelgjch1mm* al i 4an obeys the following position versus time equ 1*7jgcz tmf njlha8c1mte7. i 1la4*aation: $y = 0.50 \; \sin (\pi/2 \times t)$. What is the amplitude of vibration?
A. $0.25 \; m$
B. $0.50 \; m$
C. $0.75 \; m$
D. $1.0 \; m$
