Question

lactase is a protein in the digestive tract that helps break down certain sugars found in milk. what is the main function of lactase?
to provide structure
to fight disease
to maintain homeostasis
to regulate cell reactions

Explanation:

Lactase is an enzyme. Enzymes are proteins that regulate cell - reactions by catalyzing chemical reactions. In this case, lactase catalyzes the breakdown of milk sugars. It doesn't provide structure (like structural proteins), fight disease (like antibodies), or maintain homeostasis in a general sense as its main function.

Answer:

to regulate cell reactions