If you suspect a major deficiency of antibodies in a person, you would look for confirmatory evidence in serum globulins.

Serum globulins are a group of proteins that are found in blood plasma, and they include immunoglobulins (antibodies) as well as other proteins involved in immune function. Antibodies are a type of globulin that are produced by B cells in response to an infection or other foreign invader, and they play a critical role in the body's immune response.

A deficiency of antibodies, also known as immunodeficiency, can occur due to a variety of causes, including genetic disorders, certain medications, and infections such as HIV/AIDS. To confirm a suspected deficiency of antibodies, blood tests can be performed to measure the levels of different types of serum globulins, including immunoglobulins. If the levels of immunoglobulins are significantly lower than normal, it may indicate a deficiency of antibodies and further testing may be required to determine the cause.

So, option D, "Serum globulins," is the correct answer.