In raceme peduncle is elongated, flowers are pedicellate.
In spike, central axis is elongated but flowers are sessile.
In dichasial cyme, peduncle bears two bracts at a node from which two branches arise. 
In monochasial cyme, single lateral branch arise from peduncle of old flower which terminates in flower. The lateral branch also terminates in flower.
Therefore, the correct answer is 'A-raceme, B-spike, C-monochasial cyme, D-dichasial cyme