At body temperature, which of these combinations is most likely to result in the digestion of proteins?

Hydrochloric (HCl) acid sterilizes the food we eat and prevents harmful bacteria from entering the GI tract. HCl also triggers the release of pepsin enzymes and it is essential for the digestion of protein. Pepsinogen is pepsin's proenzyme and upon mixing with the hydrochloric acid, pepsinogen becomes pepsin.