Question

Asynchronous circuits are usually faster than synchronous circuits because
1. the frequency of the clock used is very high
2. they are free running and do not depend on the frequency of the clock
3. the orderly execution of operations in these circuits is controlled by clock pulse
4. the completion and initiation signals are not needed

Answer 1

Correct Answer - Option 2 : they are free running and do not depend on the frequency of the clock

Asynchronous circuits are usually faster than synchronous circuits because they are free running and do not depend on the frequency of the clock.

Synchronous circuit	Asynchronous circuit
All the state variable changes are synchronized with a universal clock signal.	The state variables are not synchronized to change simultaneously and may change at any time irrespective of each other to achieve the next steady internal state
Since all the internal state changes are in the strict control of a master clock source they are less prone to failure or to a race condition and hence are more reliable.	Since there is no such universal clock source, the internal state changes as soon as any of the inputs change and hence are more prone to a race condition.
Timings of the internal state changes are in our control.	The changes in the internal state of an asynchronous circuit are not in our control.