Peyer patches are part of which of the following?

A. Lymph from the lower body drains into the thoracic duct.
B. Lymph from the left side of the head drains into the thoracic duct as well, which eventually empties into the systemic circulation.
C. Lymph from the right arm does not enter the thoracic duct. It drains into the right lymphatic duct, which then empties into the systemic circulation.
D. Lymph from the left arm drains into the thoracic duct along with lymph from other parts of the body.

A. Naturally acquired active immunity occurs when the body is exposed to a pathogen, and the immune system produces its own antibodies in response. This type of immunity is not related to the transfer of antibodies from mother to fetus.
B. Artificially acquired active immunity involves vaccination, where the immune system is exposed to a weakened or inactivated pathogen to stimulate an immune response. This does not involve the transfer of antibodies from the mother.
C. Artificially acquired passive immunity involves the transfer of antibodies through medical interventions, such as antibody injections or serum treatments. While this involves passive immunity, it is not naturally occurring, nor is it related to placental transfer.
D. Naturally acquired passive immunity refers to the transfer of antibodies from mother to fetus through the placenta. These antibodies provide temporary protection to the newborn against infections, and this process is a natural example of passive immunity.