[单选题]
In the Atwood machine sho11sg pmi wu i;agc npa-1ko040wn ifuj-odq 9j-p, n Fig. 4-1, if M = 0.60 kg and m = 0.40 kg, what is the magnitude of the accelerat f9p-qjdu j,-oion of the system? (Ignore friction and the mass of the pulley.)
A. $5.3 \; m/s^2$
B. $3.9 \; m/s^2$
C. $2.0 \; m/s^2$
D. $0.98 \; m/s^2$