Two bodies of masses m1 and m2 are hung from the ends of a rope, passing over a frictionless pulley as shown in the figure below. The acceleration of the string will be

A. g (m1 - m2)/(m1 + m2)

B. 2g (m1 - m2)/(m1 + m2)

C. g (m1 + m2)/(m1 - m2)

D. 2g (m1 + m2)/(m1 - m2)

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