Which of the carbon atoms present in the molecule given below are asymmetric?(i) a, b, c, d (ii) b, c (iii) a, d (iv) a b, c

Option (ii) is the answer.

The chiral carbon, which is $sp_3$ hybridised carbon attached to four distinct substituents, is known as asymmetric carbon.
Because (b) and (c) are $sp_3$ hybridised, they have four distinct substituents linked to them, making them chiral.