What is the average lifespan of blood platelets?

Mature erythrocytes are enucleated in the following animals $EXCEPT$:
i. Rat
ii. Monkey
iii. Llama
iv. Camel
v. Elephant
Choose the correct answer from the options given below.

The probability of having a child with blood group $O$ to parents with blood groups $A$ and $B$ is

What is the percentage of hemoglobin in $RBCs$ (in $\%$)?

$A$ person having blood group $O$ can receive blood of:

Erythroblastosis foetalis is a disease in which