What Is the Chief Reason That Many People with Lactose

What is the chief reason that many people with lactose intolerance can consume foods containing some lactose without suffering any symptoms?

A) A change occurs in the GI bacteria
B) Intestinal lactase enzyme can re-appear in adequate amounts
C) The lactose-containing foods must be eaten only as part of a full meal
D) The lactose-containing foods must first be heated to 100° C to degrade lactose