Jeremy includes items that measure sexism in his index of gender roles. He does this because he ...

Jeremy includes items that measure sexism in his index of gender roles. He does this because he believes the two variables are empirically related. As a methodology student, you should tell Jeremy that:
 
  a. it's a great idea, and he should do it.
 b. if he includes both the variables in his index he is violating concerns about the general or specific dimensions of an index.
 c. if he includes both the variables in his index he needs to examine the bivariate correlations between them to be sure they are empirically correlated.
 d. if he includes both the variables in his index he is violating the criteria specifying the need for unidimensionality in index construction.
 e. great idea as long as the bivariate correlations among the variables exceed 0.9