$T$-Lymphocytes originate from

The grafting principle depends upon the

Some people who have suffered from a disease may not be affected again during their lifetime; such immunity is called

Which of the following statements is incorrect?

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

Which type of innate barrier does the $Stratum$ $corneum$ represent?