Dr Spruill Conducted a One-Way ANOVA on a Set of Data

Dr. Spruill conducted a one-way ANOVA on a set of data examining political opinions after watching different propaganda footage from different eras. Each condition saw a different reel of footage and one condition simply watched a movie with no political agenda. Dr. Spruill's one-way ANOVA yielded significant results, but it was not able to tell him where the specific difference existed. Dr. Spruill will need to follow-up with what analysis to test all possible combinations of the conditions?

A) post-hoc analyses
B) planned contrasts
C) independent sample t test
D) factorial analysis