Correct Answer - a
The phenomenon of production of emf in a coil when the current in neighbouring coil changes is called mutual induction. The coil in which the current changes is called the primary coil while the neighbouring coil in which emf is induced is called secondry coil. In addition to induced emf which is produced by mutual induction, also induced emf is produced in each coil because of self-induction Hence, option (a) is correct.