I have never used SAS before, but I need to answer some Multiple Regression problems using SAS Output

I have never used SAS before, but I need to answer some Multiple Regression problems using SAS Output. Please see the attached files. Please label the variable used in answering the question so I can understand what is done.

For a sample of people, three measurements are taken on each person (skin, thigh, arm) in an attempt to obtain variables useful in predicting their body fat (also measured). Output of SAS regression of fat on skin, thigh, and arm variables and regression of fat on skin are given on the following pages. 1. Which regression would have the smallest mean square error term if a simple regression was run of fat on each individual predictor? Why? 2. In the full model (regression of fat on skin, thigh, and arm) test the null hypothesis that the partial regression coefficients for thigh and arm are both zero versus the alternative hypothesis that at least one of them are not zero.