Correct : c

To find the data transfer rate of the DMA controller, let us calculate the number of bytes transferred per second step-by-step:
• Processor Clock Frequency: The processor operates at 4 MHz, which means it runs at a total of 4,000,000 cycles per second.
• Cycles Allocated for DMA: The DMA controller uses 1% of these processor cycles for cycle stealing:
    DMA cycles per second = 1% of 4,000,000 = 40,000 cycles/sec
• Bytes Transferred per Cycle: The DMA controller transfers 8 bytes of data in 1 cycle.
• Total Data Transferred in Bytes:
    Data rate in bytes = 40,000 cycles/sec × 8 bytes/cycle = 320,000 bytes/sec
• Convert Bytes to Bits: Since 1 byte contains 8 bits, we multiply the total bytes by 8 to get the rate in bits per second (bps):
    Data transfer rate = 320,000 × 8 = 2,560,000 bits per second (25,60,000)

Thus, the correct data transfer rate of the DMA controller is 25,60,000 bits per second, matching option (c).