What Are the Two Starting Materials for a Robinson Annulation $\alpha$

What are the two starting materials for a Robinson annulation?

A) an $\alpha$ , $\beta$ -unsaturated carbonyl compound and an enolate
B) a $\beta$ -ketoester and an enolate
C) a 1,5-dicarbonyl compound and an enolate
D) a 1,3-dicarbonyl compound and an enolate