In Order to Use a Shift Register as a Counter

Multiple Choice

In order to use a shift register as a counter, _________.

A) the register's serial input is the counter input and the serial output is the counter output
B) a serial- in, serial- out register must be used
C) the input is applied to the parallel inputs and the output is taken from the serial data output
D) the serial output of the register is connected back to its serial input