The amount of time required to read a block of data from a disk into memory is composed of seek time, rotational latency and transfer time. Rotational latency refers to
(A) the time its taken for the platter to make a full rotation
(B) the time its taken for the read-write head to more into position over the appropriate track
(C) the time it taken for the platter to rotate the correct sector under the head
(D) to reduce number of bits in the field of instruction.