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: Physiology
A young boy presents with failure to thrive. Biochemical analysis of a duodenal aspirate after a meal reveals a deficiency of enteropeptidase (enterokinase). The levels of which of the following digestive enzymes would be affected? 
Select and explain. 
A. Amylase, B. Colipase, C. Lactase, D. Trypsin
D: Trypsin
Answer: D: Trypsin 
Explanation: Enteropeptidase, formerly called enterokinase, activates trypsinogen by limited proteolytic digestion to give trypsin. Trypsin is itself capable of activating trypsinogen, which produces a positive feedback effect. Trypsin also activates chymotrypsinogen (and several other proteolytic enzymes), so deficiency of enteropeptidase results in a severe deficiency of enzymes that digest protein. Amylase aids in the breakdown of starches to oligosaccharides, maltose, and maltotriose. Colipase, along with other lipases, functions to digest fats. Lactase is a brush-border disaccharidase that hydrolyzes the bond between galactose and glucose in lactose. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 25. Overview of Gastrointestinal Function & Regulation. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.