It Is Useful to Think of Physical Capital in Terms

It is useful to think of physical capital in terms of a variable,.

A) stock; because any flow of investment adds to the current capital stock
B) stock; because most equipment is solidly built
C) stock; depending on the context
D) flow; because it is usually put in place and maintained over a long period of time
E) flow; because its usefulness lasts over a long period of time