Two mutually exclusive projects have conventional cash flows, but one project has a larger NPV while the other project has a higher IRR. Which of the following least likely explains this conflict（）

A. Reinvestment rate assumption.

B. Size of the projects’ initial investments.

C. Risk of the projects as reflected in the required rate of return.

关于突触前抑制的叙述，正确的是

A．突触前膜超极化
B．突触后膜超极化
C．突触前膜去极化
D．突触后膜去极化
E．没有神经递质参与