Multiple-Object Systems Without Friction: a Wooden Block a of Mass

Multiple-object systems without friction: A wooden block A of mass 4.0 kg slides on a frictionless table when pulled using a massless string and pulley array by a hanging box B of mass 5.0 kg, as shown in the figure. What is the acceleration of block A as it slides on the frictionless table?
Hint: Think carefully about the acceleration constraint.

A) 4.1 m/s²
B) 3.5 m/s²
C) 3.1 m/s²
D) 2.7 m/s²