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

Fill in the blanks: Our body, when it encounters a pathogen for the first time, produces a response called . . . . . . $a$ . . . . . . response, which is of . . . . . . $b$ . . . . . . intensity. Subsequent encounters with the same pathogen elicit a . . . . . . $c$ . . . . . . intensified . . . . . . $d$ . . . . . . response.

What are interferons? How do interferons check infection of new cells?

What do antibodies fight against?

Assertion: Interferons are effective against viruses.
Reason: Proteins which can be synthesized only by genetic engineering are effective against viruses.

Identify the set of secondary lymphoid organs from the following.