Which of the following is a function of the lymphatic system?

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.

A. Attenuation is the process of weakening or reducing the virulence (ability to cause disease) of a pathogen, making it less harmful. This weakened form can then be used in the preparation of vaccines, allowing the immune system to respond without causing disease.
B. Antitoxin refers to antibodies or other substances that neutralize toxins, not the process of reducing a pathogen's virulence.
C. Complement refers to a group of proteins that play a role in the immune response, enhancing the ability to clear pathogens, but it is not related to the process of preparing vaccines.
D. Vaccine is a preparation used to stimulate the immune system, but the process of preparing the vaccine (such as attenuation) is different from the vaccine itself.