Which of the following is the correct definition of a counter?

a$.$

A group of flip$-$flops, each one of which shares a common clock and is capable of storing one bit of imformation.

b$.$

A clocked sequential circuit that consists of flip$-$flops and combinational gates.

c$.$

A register that goes through a prescribed sequence of states upon the application of input pulses.

d$.$

A group of flip$-$flops, without any gates.