14) When regressing the outcome variable Y on a binary treatment indicator X, Yi - Bo+ BIX; + up 1= 1,...,n, then all of the following statements are true EXCEPT for: A) there should be no intercept since the difference estimator eliminates it. B) Bo is an unbiased and consistent estimator of the causal effect. () you should use homoskedasticity-only standard errors since it is likely that the variance in the treatment and control group are the same. D) Bo gives you the mean of the control group. 15) Small sample sizes in an experiment: A) biases the estimators of the causal effect. B) may pose a problem because the assumption that errors are normally distributed is dubious for experimental data. C) do not raise threats to the validity of confidence intervals as long as heteroskedasticity-robust standard errors are used. D) may affect confidence intervals but not hypothesis tests