Final answer:
Individuals who are Le(a-b-) can develop Lewis antibodies without direct exposure to Lewis antigens, and these are classified as Naturally occurring antibodies due to similar environmental exposures.
Step-by-step explanation:
Individuals who are Le(a-b-) and can develop Lewis antibodies without exposure to Lewis antigens are called Naturally occurring. Often, antibodies are made when the body is exposed to a foreign antigen. For example, those with ABO blood type A will naturally have anti-B antibodies without exposure to B antigens, and this is due to the immune system's response to similar antigens encountered in the environment, like in certain foods and bacteria. Hence, the antibodies that people with the Le(a-b-) phenotype can develop without exposure to the specific Lewis antigens are also classified as naturally occurring.