[单选题]
In the Atwood machinp1s* g (sk1oodjmq+2 yq)*cqh gz4-)b bq8m dye shown in Fig. 4-1, if M = 0.60 kg and m = 0.40 kg, what is the tension in the string? (Ignore friction and the may-)dgmqbb 84zss of the pulley.)
A. $3.1 \; N$
B. $4.7 \; N$
C. $7.1 \; N$
D. $7.5 \; N$