Thesub-multipleprefix“micro”means（）. A: thousandth(10tothe-3rdpower) B: millionth(10tothe-6thpower) C: billionth(10tothe-9thpower) D: trillionth(10tothe-12thpower)

We usually measure the processing speed in today’s computer according to the A: thousandthof a second B: millionthof a second C: billionthof a second D: trillionth of a second