Select the correct statements regarding the characteristics of acquired immunity.
(i) Cell-mediated immunity is responsible for acquired immunity.
(ii) It produces a primary response of low intensity.
(iii) Active and passive immunity are types of acquired immunity,
(iv) Polymorphonuclear leucocytes and natural killer cells are involved in acquired immunity.

Options

A. (i), (ii) and (iii)
B. (i), (iii) and (iv)
C. (i) and (iv)
D. (i) and (iii)

Answer

A

Explanation

Acquired immunity is the type of immunity acquired during life time. Both cell-mediated immunity (mediated by T-cells) and humoral immunity (mediated by B-cells) are responsible for acquired immunity. Acquired immunity is characterised by memory. This means that when our body encounters a pathogen for the first time, it produces a response called primary response which is of low intensity. Active immunity and passive immunity are types of acquired immunity. Polymorphonulear leucocytes and natural killer cells are involved in innate immunity. These cells phagocytose and destroy microbes.