Some individuals are unable to eat or drink dairy products containing lactose. what causes them to be unable to tolerate lactose in their diet? a) they are allergic to proteins from cattle. b) they lack an enzyme that breaks down lactose. c) there is an abnormality in the lining of their small intestine. eliminate d) they are unable to absorb the products from the breakdown of lactose.

B

Explanation:

These persons are known as lactose-intolerant. Because they have no enzymes that breakdown lactose (lactase enzymes), the lactose is not broken down in the digestive tract, and becomes ‘fodder’ for the microbiome bacteria in the colon. The bacteria break down the lactose releasing gases as byproduct hence causing symptoms such as bloating- due to gases - to the person.  

Lactase enzyme concentration are usually high in infants so they can digest the milk from lactation. However, during weaning this lactase concentration decreases. This is called primary lactase deficiency. Secondary lactase deficiency occurs when there is injury to the bowel mucosal due to injury (maybe from ana infection). There is another rare lactase deficiency called congenital. It is found in infants who are unable to digest milk during lactation.

the answer is :

not always but somethings can be reproduced in a laboratory.