[单选题]
An object in simple har0mcn4vv* :5crztm2ueet x 6tvsj -*5 ymonic uz:bg7j7 n+1 w5 grpsqghy-z;motion obeys the following position versus time equatgsrj7p57q : y-n gbzgh 1wuz;+ion: $y = 0.50 \; \sin (\pi/2 \times t)$. What is the maximum speed of the object?
