A great deal of human invention since the last 300 years has been directed to taming the power hidden in nature, and to channeling it into steady sources of energy that can drive machines.

A great deal of human invention since the last 300 years has been dire

1.	A great deal of human invention since the last 300 years has been directed to taming the power hidden in nature, and to channeling it into steady sources of energy that can drive machines.
A.	ince the past 300 years
B.	n the last 300 years
C.	uring the past 300 years
D.	o improvement
Answer» D. o improvement