Why Did Scientists Originally Hypothesize That Proteolytic Enzymes Like Pepsin

Why did scientists originally hypothesize that proteolytic enzymes like pepsin and trypsin are secreted in inactive form?

A) These proteolytic enzymes,in active form,would digest the very tissues that synthesize them.
B) They identified the hormone that activates pepsin and trypsin.
C) The stomach is too acidic to maintain these enzymes in their active form.
D) Upon study of chief cells,they were able to isolate active forms of pepsin and trypsin.