Read the passage and answer the question given below.
When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body. This type of immunity is called active immunity. Active immunity is slow and takes time to give its full effective response. Injecting the microbes deliberately during immunisation or infectious organisms gaining access into body during natural infection induce active immunity. When antibodies are directly given to protect the body against foreign agents, it is called passive immunity.
Which of the following is passive immunisation?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → injecting preformed antibodies
Option (1) injecting inactivated pathogens — Incorrect. Inactivated pathogens make the body produce its own antibodies; that is active immunisation (vaccination).
Option (2) injecting antigenic preparation — Incorrect. Antigenic proteins also lead to the body's own antibodies and memory cells: active.
Option (3) injecting preformed antibodies — Correct. The antibodies act at once, as in anti-tetanus injections or snake antivenom, but give no memory.
Option (4) injected weakened pathogens — Incorrect. Weakened pathogens also cause active immunity.
Note: The passage is taken from NCERT. NTA has put lines of the NCERT text together to make it. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.