You are performing two sums, the first is a sum of two scalar variables and the second is a matrix sum of a pair of two— dimensional arrays—size 1000 by 1000. What speedup is achieved when the calculations are performed on size 1000 processors ( )

A．堆栈型
B．累加器型
C．寄存器型
D．通用寄存器与累加器混合型

A．It prevents overflow
B．It prevents underflow
C．It preserves the sign of the multiplication operation
D．It enhances the speed of the operation significantly