- Natural Active Immunity: Immunity developed after exposure to a pathogen through natural infection (Set II: 2. Acquired after small pox infection). - Natural Passive Immunity: Antibodies are transferred naturally from one person to another, e.g., from mother to child through placenta or breast milk (Set II: 3. Transferred from mother to child). - Artificial Active Immunity: Immunity developed after intentional exposure to an antigen, usually through vaccination (Set II: 4. Develops due to vaccination). - Artificial Passive Immunity: Antibodies are introduced into a person's body from an external source, e.g., through antiserum injection (Set II: 1. Anti-rabies serum).