Classify the following as definitions or specific examples of primary or secondary lymphoid organs. a. Lymphocytes frequently migrate from the blood into these lymphoid organs, where they may encounter foreign molecules or cells. b. An example of this type is found in bones of children and focused in the bones of the skull, ribs, and vertebral column of adults. c. Lymphoid organs in which lymphocytes develop and mature d. Red bone marrow e. Lymphoid organs in which some lymphocytes become activated f. Lymph nodes