Hitting Time on the Diamond Graph

Take the complete graph $K_4$ on vertices $\{A, B, C, D\}$ and remove edge $A{-}D$, leaving $5$ edges (the "diamond" or "kite" graph). The resulting degrees are $d(A) = d(D) = 2$ and $d(B) = d(C) = 3$. A simple random walk moves at each step to a uniformly random neighbor.

(a) Starting from vertex $A$, find the expected hitting time $h(A \to D)$.

(b) Starting from vertex $D$, find $h(D \to A)$.

(c) Compute the commute time $C(A, D)$ and verify it using the effective-resistance formula.