砌体房屋抗震计算时，在下列几种情况中，哪一项是不正确的（）。

A.底层框支墙梁房屋的抗震计算，可采用底部剪力法。底层的纵向和横向地震剪力设计值均应乘以增大系数，其值允许根据第二层与底层侧向刚度比值的大小在1.2～1.5范围内选用

B.底层框架一抗震墙房屋，考虑高阶振型的影响，顶点需附加水平地震作用，其附加地震作用系数取δn=0.2

C.在楼层各墙段间进行地震剪力分配时，当墙段的高宽比h/b＜1时，墙段的层间等效侧向刚度只按剪切变形考虑

D.对于考虑地震作用组合的砌体自承重墙，当进行墙体截面抗震承载力验算时，其受剪承载力抗震调整系数γRE=0.75

A shop foreman determines that an employee would produce two more units of output ff he worked one additional hour. The product currently sells for $15.00 per unit and the firm is a price taker. Which of the following choices most accurately describes the relationship between the marginal revenue (MR) and marginal revenue product (MRP) from the additional hour of labor input（）

A. MRP ＞ MR.

B. MRP = MR.

C. MR ＜ $15 and MRP = MR.