A weight W is tied to a trolley of mass M by a light string passing over a frictionless pulley. The trolley has an acceleration a on a frictionless table. The acceleration due to gravity is g.

What is W ?

A.    \(\frac{{Mag}}{{(g - a)}}\)

B.    \(\frac{{Mag}}{{(g + a)}}\)

C.    \(\frac{{Ma}}{{(g - a)}}\)

D.     \(\frac{{Ma}}{{(g + a)}}\)

A