In the Equation $R \times p _ { k } = M P K + \Delta p _ { k } , \Delta p _ { k }$

In the equation $R \times p _ { k } = M P K + \Delta p _ { k } , \Delta p _ { k }$ is the ________ and $p _ { k }$
Is the ________.

A) stock return; bond return
B) return from a bank account; return to owning capital
C) capital gain; initial price of capital
D) real interest rate; rate of return to capital
E) opportunity cost of capital; user cost of capital