The three objects in the drawing are connected by strings that pass over massless and friction-free pulleys, and are all initially at rest. The coefficient of static friction between the middle object and the surface of the table is 0.15 , while the coefficient of kinetic friction is 0.12 . What is the acceleration (in m/s2) of the middle object? a. 0, the middle object does not start moving due to the static friction. b. 0.047 c. 0.60 d. 0.46 e. 1.28