Answer:
B. Involves a ylide as a reactant/intermediate
C. Results in a betaine intermediate
Step-by-step explanation:
The Wittig reaction is the reaction of an aldehyde or ketone with a triphenylphosphonium ylide to form an alkene.
A betaine intermediate is the precursor to an oxaphosphetane intermediate.
A. is wrong. The ylide is a reactant/intermediate.
D. is wrong. The reactant can be an aldehyde
E. is wrong. A C=O bond becomes a C=C bond.