What is the primary difference between passive and active immunotherapy?

• A. Both passive and active immunotherapy stimulate the patient's immune system.
• B. Passive immunotherapy uses antibodies directly, while active immunotherapy stimulates the patient's immune system.
• C. Active immunotherapy uses antibodies directly, while passive immunotherapy stimulates the patient's immune system.
• D. Passive immunotherapy is more effective than active immunotherapy.

Answer: (B)