$S$ is the so$-$called pre$-$master secret

a $K=h(S,R_A,R_B)$

$"$msgs$"$ means all previous messages

$$CLNT and SRVR are constants

In the diagram above, $h(msg1,K)$ indicates hash of $"$msg$1"$ using key $K$ with constants $R_A,R_B$;

$E(msg2,K)$ indicates symmetric key encryption of $"$msg$2"$ with key $K.$

If we number the messages in the above diagram from top to bottom as $1$ through $5,$ why is

Bob convinced that he is talking to Alice after message $3?$

Other than Bob, only Alice knows S

Other than Bob, only Alice can compute K

Other than Bob, only Alice could compute the h$($msgs$,$ CLNT$,$K$)$

All of the above