A personnel officer in a governmental agency administered four newly developed aptitude tests to each of 25 applicants for entry-level clerical positions in the agency. all 25 applicants were accepted for positions irrespective of their test scores

X1, X2, X3, X4 = the test scores

Y = job proficiency score

Data set is available https://netfiles.umn.edu/users/nacht001/www/nachtsheim/Chapter%20%209%20Data%20Sets.html (CH09PR10)

A. Using only first-order terms for the predictor variables in the pool of potential X variables, find the four best subset regression models according to the R^2 a,p criterion

B. since there is relatively little difference in R^2 a,p for the four best subset models, what other criteria would you use to help in the selection of the best model? discuss

I NEED R CODES FOR BOTH QUESTIONS. (IF APPLICABLE)