provides passive immunity

"Graveyard of $RBCs$'' 

Given below are two statements :

Statement $I$ : Bone marrow is the main lymphoid organ where all blood cells including lymphocytes are produced.

Statement $II$ : Both bone marrow and thymus provide micro environments for the development and maturation of T-lymphocytes.

In the light of above statements, choose the most appropriate answer from the options given below :

‘Second line of defence' is known as

For an organ transplant, it is an advantage to have an identical twin. Why ?

Antivenom injection contains preformed antibodies while polio drops that are administered into the body contain