Simplify:
A3a²b + 4a²b - a²b =
B3a²b + 4ab² + 2a²b =
C3a²b + 4a² + a²b + 6a² =
D3a²b +4a² + a²b + 6b² =
A3a²b + 4a²b - a²b =
B3a²b + 4ab² + 2a²b =
C3a²b + 4a² + a²b + 6a² =
D3a²b +4a² + a²b + 6b² =