"Higher forms of animal life have a variety of systems within their bodies that are used for special functions: a circulatory system for he blood; the food supplier; a digestive system for converting food into energy and body tissue; and others.

The definition that applies to "converting" is
A) making a goal after receiving a pass
B) exchanging for an equivalent
C) alternating the physical or chemical nature
D) diverting from one destin to another
Is it B?

I agree.