This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
The Co-enzyme required for the synthesis of fatty acid synthesis is: 
Select and explain. 
A. FAD, B. FADH2, C. NAD, D. NADPH
D: NADPH
Answer: D: NADPH 
Explanation: The Main Source of NADPH for Lipogenesis Is the Pentose Phosphate Pathway.
The pentose phosphate pathway is an alternative route for the metabolism of glucose. It does not lead  to formation of ATP but has two major functions:

The formation of NADPH for synthesis of fatty acids and steroids, and maintaining reduced  glutathione for anti- oxidant activity.
The synthesis of ribose for nucleotide and nucleic acid formation.

Ref:Harper's Illustrated Biochemistry 30th Edition 196