Which foods would be most likely to cause symptoms of lactose intolerance why?

Is this a homework problem. I will give you a tip but not an answer. Lactose is the kind of natural sugar in milk. A person who has lactose intolerance does not have the enzymes needed to digest lactose. If a person is lactose intolerant, the greater amount of milk product the person eats, the more symptoms of lactose intolerance he will have.