Option b is correct. The output pattern that is observed at QA in the first four clock cycles is 0110.
The ability of a flip-flop to toggle or switch between its two states, the "toggle state" and the "memory state," gives rise to the term "toggle flip-flop." A T-type flip-flop is perfect for use in binary counter construction and frequency division because there are just two states.
By connecting the output of one to the clock input of the next, "Toggle" or "T-type flip-flops" can be used to create binary ripple counters. Since toggle flip-flops change from one state to another (HIGH to LOW or LOW to HIGH) at each clock cycle, they are perfect for building ripple counters. Simple frequency divider and ripple counter circuits can be easily built using conventional T-type flip-flop circuits.
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