Why is the answer (B)? Please show math and explanation.

A uniform turntable of mass M = 1.2 kg and radius R = 2 m can rotate freely around a vertical axis. A toy car of mass m = 0.4 kg is placed at the rim of the turntable. A B 7. Initially, the car and the turntable are at rest (A). Then, the toy car starts to move around the vertical axis along the rim of the turntable with an angular speed w = 2.0 rad/s (observed by a stationary observer) (B). What is the magnitude of the total angular momentum of the turntable and the toy car after the toy car starts to move? a. 8.0 kg.m /s b. 0 kg.m-/s c. 4.8 kg.m /s d. 3.2 kg.m /s e. 1.2 kg.m /s