Solution
= Solution
Induct on $\gamma$. Part (b) gives a member of rank at least $\gamma$; transitivity and descent through a member of larger rank, using the induction hypothesis, produces a member of rank exactly $\gamma$.
= Solution
Induct on $\gamma$. Part (b) gives a member of rank at least $\gamma$; transitivity and descent through a member of larger rank, using the induction hypothesis, produces a member of rank exactly $\gamma$.