Correct Answer:
C. Clock
The correct answer is Clock. In a computer system, the system clock is responsible for setting and maintaining the timing for data transfer operations. The clock generates a continuous stream of electrical pulses (clock cycles) that synchronize the activities of the CPU, memory, and other components. Data transfer occurs at specific intervals defined by these clock cycles. The PSU (Power Supply Unit) provides power, the CPU processes data, and the CU (Control Unit) directs operations, but none of these specifically set timing for data transfer. Therefore, the Clock is the correct component.