Planned Comparisons After an ANOVA Using the T-Test Procedure Tend

Multiple Choice

Planned comparisons after an ANOVA using the t-test procedure tend to have higher precisions than regular two-sample t-tests. Why is that?

A) The chosen pair of groups will always have the largest difference from among all the groups in the ANOVA.
B) The degrees of freedom value used to define the confidence intervals is always larger.
C) The MS_error is always less than the pooled variance.
D) The standard error is always less using all the groups rather than just two.