Select the scenarios that can result in active immunity.Multiple select question.Infection with a pathogenAntibodies cross the placentaBone marrow transplantPlasma transfusions to treat Ebola virus infectionImmunization with a vaccine

The scenarios that can result in active immunity are:

1. Infection with a pathogen
2. Immunization with a vaccine

Explanation:

Active immunity is the immunity that results from the production of antibodies by the immune system in response to the presence of an antigen.

1. Infection with a pathogen: When a pathogen (like a bacteria, virus, or other disease-causing organism) enters the body, the immune system responds by producing antibodies. This process can take several days, but once complete, the body has a supply of antibodies that can quickly respond to future infections by the same pathogen. This is a form of active immunity because the body's immune system is actively involved in producing the antibodies.

2. Immunization with a vaccine: Vaccines work by introducing a weakened or dead version of a pathogen, or a piece of a pathogen, into the body. This stimulates the immune system to produce antibodies against the pathogen, without causing the disease. This is also a form of active immunity because the body's immune system is actively involved in producing the antibodies.

The other options do not result in active immunity:

• Antibodies cross the placenta: This is an example of passive immunity, where the mother's antibodies are passed to the baby to provide temporary protection.

• Bone marrow transplant: This procedure can help to create a new immune system, but it does not directly result in active immunity.

• Plasma transfusions to treat Ebola virus infection: This is also an example of passive immunity, where antibodies from a person who has recovered from Ebola are given to a person infected with the virus.