i think its 200Mhz
two flipflops are operated one after the other(we can see o/p of first FF is clock of 2nd FF) and last flipflop one can be operated in parellel to 1st flipflop.(as there is comn clock for 1st and 3rd FF)
Tclock = Tcombi +2*Tflipflop
Tclock= 1+2*2
Tclock=5ns
frequency = 1/5GhZ = 0.2GHZ = 200MHZ