Sequential circuits are represented asa.infinite state machineb.finite state machinec.finite synchronous circuitd.infinite asynchronous circuit

Sequential circuits are represented as a finite state machine.

Here's why:

1. Sequential circuits are a type of digital circuit where the output depends not only on the present input but also on the history of the input. This is unlike combinational circuits where output only depends on the present input.

2. In a sequential circuit, the output state moves from one state to another based on the input and the current state. This is why it's called a "state machine".

3. The number of states in a sequential circuit is finite, determined by the number of flip-flops used in the circuit. Each flip-flop represents one binary digit or bit, so for example, three flip-flops can represent up to 2^3 = 8 states.

4. Therefore, a sequential circuit is a "finite state machine". It's not an "infinite state machine" because the number of states is limited by the number of flip-flops. It's not an "infinite asynchronous circuit" or a "finite synchronous circuit" because these terms are not standard terms used in digital circuit design.