Suppose that a researcher considers the following regression model,

(1) INC_i = ₀ + ₁FEM_i +₂MARRIED_i +₃AGE_i + _i

where INC_i is individual is annual income ($/year), AGE_i is is age, and FEM_i and MARRIED_i are dummy variables representing, respectively, is gender (FEM_i = 1 if i is female and 0 if male) and marital status (MARRIED_i = 1 if i is married, and 0 if not married).

In this model, which of the following is the base (or reference) case?