The best method of analysing a pre-treatment, post-treatment design which includes a control group is?

A- To find the difference scores between pre- and post-treatment and run an ANOVA on the difference scores

B- A two-way mixed ANOVA

C- To find the difference scores between pre- and post-treatment and run a t-test on the difference scores

D- ANCOVA with the pre-treatment scores as a covariate