For Any Given Year, the Capital Stock Can Be Considered

For any given year, the capital stock can be considered to be exogenously determined because

A) usually gross investment just matches depreciation, so that the capital stock is fixed.
B) investment projects, even in excess of depreciation, generally take more than 12 months to install.
C) accounting conventions subtract depreciation of the capital stock from gross investment in their computation of net investment for the year.
D) interest rates, the price of capital, hardly ever move significantly over the course of any 12-month period.
E) all of the above.