Given below are two statements. One is labelled Assertion (A) and the other is labelled Reason (R).

Assertion (A): People with O -ve blood type are called 'universal donors'.

Reason  (R): RBC of O -ve blood type lack antigens (A, B and Rh) that trigger an immune response in the recipient.

In light of the above statements, choose the correct answer from the options given below.

Both (A) and (R) are true and (R) is the correct explanation of (A).

Assertion (A) states that people with O-negative blood type are called "universal donors." This is true because individuals with O-negative blood type lack A, B, and Rh antigens on their red blood cells, which reduces the likelihood of an immune response in the recipient.
Reason (R) provides an explanation for Assertion (A), stating that RBCs of O-negative blood type lack antigens (A, B, and Rh) that trigger an immune response in the recipient. This is also true because, unlike other blood types (A, B, and AB), type O red blood cells lack both A and B antigens on their surface. O -ve people lack D (Rh) antigen also. These antigens are proteins that can trigger an immune response in individuals with different blood types. Therefore, individuals with type O blood can safely donate red blood cells to people of any other blood type without causing an adverse immune reaction. This makes them universally compatible as red blood cell donors in emergency situations where time may not allow for determining the recipient's blood type.