Secretion of interferon is which type of barrier?

Which factor is responsible for autoimmunity?

How many types of barriers are included in innate immunity?

Select the lymphoid organs from the given choices:
$I$. Lymph node $II$. Thymus gland
$III$. Red bone marrow $IV$. Liver
$V$. Spleen $VI$. Osteocytes
$VII$. Peyer's patches
The correct option is:

Passive immunity was discovered by

Assertion $(A)$: Antigen can be easily recognized because it has antigenic determinants.
Reason $(R)$: The recognition ability is innate.