The correct answer is: B. 8 MHz
The Z80 is a 8-bit microprocessor that was designed by Zilog in 1976. It was one of the most popular microprocessors of the 1970s and 1980s, and it is still used in some embedded systems today. The Z80 has a clock frequency of 8 MHz, which means that it can execute 8 million instructions per second.
The other options are incorrect because they are not the clock frequency of the Z80. Option A is 6 MHz, option C is 4 MHz, and option D is 2 MHz.
The clock frequency of a microprocessor is the number of cycles per second that the microprocessor’s internal clock runs at. The higher the clock frequency, the faster the microprocessor can execute instructions. However, the clock frequency is not the only factor that determines the speed of a microprocessor. Other factors include the number of transistors in the microprocessor and the design of the microprocessor’s instruction set.