Setup and hold time output when violated
If the flip-flop's setup time is 20 ns, it means that data has to be stable atleast 20ns before the capturing clock-edge. Similarly hold time is the amount of time, data has to remain stable after a clock edge has appeared. So together they define a "setup-hold-window", in which data has to remain stable. 


If the data changes/toggles within this window, the output is unpredictable or metastable. 

In your question data toggles within the setup window prior to the 6th clock edge, means the output is unpredictable.