Which relative clause can be reduced?

✂️ a) Sam is dating the woman who is wearing a black hat.

✂️ b) Philadelphia is the city in which Rocky Balboa lived.

✂️ c) The dog which bit the kid will be sacrificed.

✂️ d) Anyone who touches that wire will get a shock.

✂️ e) He spoke Greek, which impressed me.

Responda: Which relative clause can be reduced?