The "Before and After" Specification, Binary Variable Specification, and "Entity-Demeaned

Multiple Choice

The "before and after" specification, binary variable specification, and "entity-demeaned" specification produce identical OLS estimates

A) as long as there are observations for more than two time periods.
B) if you use the heteroskedasticity-robust option in your regression program.
C) for the case of more than 100 observations.
D) as long as T = 2 and the intercept is excluded from the "before and after" specification.