单项选择题
WhichofthefollowingisthedefinitionofCASlatency？（）
A.CASlatencyistheratiobetweenthecolumnaccesstimeandtheclockcycletime.
B.CASlatencyistheratiobetweentherowaccesstimeandtheclockcycletime.
C.CASlatencyistheratiobetweenthecolumnaccesstimeandthedatabursttransfertime.
D.CASlatencyistheratiobetweentherowaccesstimeandthedatabursttransfertime.