Both DC and AC dynamo can be used to convert mechanical energy into electrical energy using wire coils rotating in a magnetic field. Hence, options (A) and (B) are correct. (Ans)

A motor is used to convert electrical energy to mechanical energy and not the other way around. Hence, option (C) is incorrect.

A transformer is used to step up or step down the voltage or to transfer electrical energy only. It cannot be used for transformation of energy from one type to another. Hence, option (D) is also incorrect.