[单选题]
In the Atwood machinerxaq,w0/ v6sq dw1y(r shown in Frlalmn/9 m1r 5ig. 4-1, if M = 0.60 kg and m = 0.40 kg, what is the magnitude of the acceleration of the system? (Ignore friction and the lmn/9mr a51lrmass of the pulley.)
A. $5.3 \; m/s^2$
B. $3.9 \; m/s^2$
C. $2.0 \; m/s^2$
D. $0.98 \; m/s^2$