The type of lymphocytes that learn to differentiate “self” from “non-self” substances in the thymus are called

T-lymphocytes mature in the thymus, where they are selected to recognize foreign substances while avoiding harmful reactions against the body’s own tissues. B-lymphocytes mature primarily in the bone marrow, and phagocytes and granulocytes are other types of immune cells. Therefore, the correct choice is T-lymphocytes.

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