确认一下思路

问题如下：

Compared to the assumptions Stereo Warehouse used to compute its periodic pension cost in 2008, earnings in 2009 were most favorably affected by the change in the:

选项：

discount rate.

estimated future salary increases.

expected long-term rate of return on plan assets.

解释：

B is correct.

In 2009, the three relevant assumptions were lower than in 2008. Lower expected salary increases reduce the service cost component of the periodic pension cost. A lower discount rate will increase the defined benefit obligation and increase the interest cost component of the periodic pension cost (the increase in the obligation will, in most cases, more than offset the decrease in the discount rate). Reducing the expected return on plan assets typically increases the periodic pension cost.

考点：养老金会计的假设

解析：题目问选项ABC三个假设的变化，那个对2009年NI有有利影响。有利影响可能来自两方面，一方面是增加income，另一方面是减少expense。

首先，明确2009年的这三个假设的数值都小于2008年的假设。

A选项：lower discount rate，会导致PBO变大，导致interest cost增加，NI降低。（因为pension的maturity通常是很久的，可以类似于债券的duration，此时PBO增长比discount rate减少对interest cost的影响更大）

B选项：Lower expected salary increases ，预期退休后的工资水平变低，那么公司未来要打给员工的退休金就会变少，因为退休金一般是基于final salary计算出来的。未来养老金支出减少，当前PBO就会减少，对应的interest expense和current service cost都会下降，所以NI上升。

C选项Expected long-term rate of return on plan assets的降低，也就是E(R)降低，美国准则下损益表中的expected return用E(R)计算，E(R)降低则expected return减少，NI会降低。

因此，选项B正确，只有该项是有利影响，其他都是不利影响。