Transfer rate=10 MB per second
Data=20 KB=20* 2 10
So Time=(20 * 2 10)/(10 * 2 20)= 2* 10-3 =2 ms
Processor speed= 600 MHz=600 Cycles/sec
Cycles required by CPU=300+900 =1200
For DMA=1200
So time=1200/(600 *10 6)=.002 ms
In %=.002/2*100=.1%
So (D) is correct option