$.$ In Diffie Hellman Key Exchange, everyone agrees on a well$-$known large prime p and a corresponding number g such that $1<$ g $<$ p$-1.$ Alice picks a random secret a $(1<$ a $<$ p$-1)$ and Bob picks a random secret b $(1<$ b $<$ p$-1).$ Diffie Hellman Key Exchange process establishes the shared secret key K where

Group of answer choices

K$=$ g$^$a mod p

K$=$ g$^$b mod p

K$=$ g$^$ab mod p

None of the above