A is B's brother, C is B's mother, D is C's father. How is A related to D? MCQ with Answer and Explanation

Explanation:
Differences: +5, +10, +15, +20, so next difference is +25: 56+25=81.

Explanation:
C is father of A, D is sister of C so D is paternal aunt of A. E is brother of B, B is child of A, so E is grandchild of C. D is sister of grandfather, i.e., great aunt of E.

Explanation:
Each letter +1: M→N, I→J but given N C Q... Not matching. Perhaps reverse and +1. MIRACLE reversed ELCARIM +1 → FMD BSJN not. Perhaps different. Standard +1 for each: but given NCQBNMD is M+1=N, I+1=J not C. Perhaps skip.