What does $CMI$ stand for?

Which of the following is an autoimmune disease?

Antibodies produced by $B$-lymphocytes are responsible for:

An antiviral chemical produced by the animal cell is

How many heavy polypeptide chains are present in each antibody molecule?

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