A researcher conducts research on optimism. The researcher is calculating a multiple regression ...

A researcher conducts research on optimism. The researcher is calculating a multiple regression equation to predict levels of optimism and wishes to consider religious affiliation as one of the predictor variables.
 
  The researcher creates several dummy variables for this purpose. Why must this be done? (Select all that apply.)
  a. It is safer to create more variables than fewer, since they may each contribute.
  b. Multiple regression requires that the researcher enter numerical values, not names such as Lutheran, Orthodox Jewish, Buddhist, Islamic, and so forth.
  c. Reducing nominal or categorical data to one or a series of dichotomous values allows mathematical computation of the regression equation.
  d. Religious affiliation is a protected entity under HIPAA and must be coded before it is used in calculations.
  e. The researcher's aim is to develop a formula with which to calculate optimism, given certain other variables, so these must all be represented as numbers.