$A$ person is injected with globulin against hepatitis. This is an example of:

Name the primary and secondary lymphoid organs.

Which type of antibody is produced in the body against the body's own cells in rheumatoid arthritis?

What type of immunity is provided by the treatment given against snake bites?

Read the given statements carefully and identify the incorrect statements.
$(1)$ In active acquired immunity,antibodies are directly injected into the body.
$(2)$ Vaccination is considered under passive acquired immunity.
$(3)$ The human body distinguishes between self and non-self with the help of $Tc$ cells.
$(4)$ Innate immunity consists of four types of barriers.

Where are $B$-cells and $T$-cells formed? How do they differ from each other?