Feasible WLS Does Not Rely on the Following Condition

Multiple Choice

Feasible WLS does not rely on the following condition:

A) the conditional variance depends on a variable which does not have to appear in the regression function.
B) estimating the conditional variance function.
C) the key assumptions for OLS estimation have to apply when estimating the conditional variance function.
D) the conditional variance depends on a variable which appears in the regression function.