An analyst conducts a two - tailed test to determine whether differences between the means of two populations exist: H₀: μ1-μ2=0 versus H₂: μ1-μ2≠0. Assume that the populations are independent, normally distributed, and have unequal and unknown variances. The critical value with 50 degrees of freedom is 2.126. The computed test statistic is t=1.753. Using a significance level of x=0.05, which of the following statements is TRUE（）

A. Use a t- test to reject the null hypothesis and accept the alternative hypothesis.

B. Use a t -test to accept the null hypothesis and reject the alternative hypothesis.

C. Use a z- test to reject the null hypothesis and accept the alternative hypothesis.

大海公司2008年生产甲产品，计划产量为2000件，计划单位成本为100元，实际产量为2400件，累计实际总成本为235200元。假定将甲产品的实际成本与计划成本比较。2008年甲产品计划成本降低率为( )元。

A．2%(超支)

B．2%(节约)

C．2.4%(超支)

D．2.4%(节约)