A System Comprised Blocks, a Light Frictionless Pulley, and Connecting

Multiple Choice

A system comprised blocks, a light frictionless pulley, and connecting ropes is shown in the figure. The 9.0-kg block is on a perfectly smooth horizontal table. The surfaces of the 12-kg block are rough, with µ_k = 0.30 between the block and the table. If the 5.0-kg block accelerates downward when it is released, find its acceleration.

A) 1.0 m/s²
B) 1.2 m/s²
C) 1.4 m/s²
D) 1.6 m/s²
E) 1.8 m/s²