After hitting the power wall in 2004and unable to continue to increase clock frequencies, processor manufacturers turned to multiple coresfor more performance. Why were they reluctant to do this earlier?

a)The multiple cores took up room that was needed for larger caches.

b)Serial programs will only run on one core.

c)It is expensive to wire separate processor cores together and hard to put the tiny wires on.

d)4 cores cost 4X as much as one.

e)None of the above answers are correct.