The functional difference between $SR$ flip-flop and $J$-$K$ flip-flop is that :
The main difference between a JK flip-flop and an SR flip-flop is that in the JK flip-flop, both inputs can be HIGH. When both the J and K inputs are HIGH, the Q output is toggled, which means that the output alternates between HIGH and LOW. Thereby the invalid condition which occurs in the SR flipflop is eliminated.
Hence,Option(C)JK flip-flop accept both input 1.
JK FF is SR FF + 2 latches, so definitely not faster than SR FF. Option A eliminated
Option B is incorrect, because every FF has that. It's not a "functional difference".
Option C is correct. It accepts 11 and toggles on it.