Answer: All of the given options.
Explanation:
The body generates immune response to every antigen that it encounters. Some of the responses are general response and some of the response are specific response.
The first line of defense is skin and mucous membrane which is a general response of the body in which the skin and mucous membrane helps in preventing the body from entry of organisms.
The second line of defense includes interferon and group of some cells like basophills, neutrophills ( types of leukocytes). They travel in blood and kills the pathogen present in blood.
The third line of defense includes B-cells and T-cells( type of leukocytes) which is specific to antibodies which means they will attack specific antigens and kill them.
Hence, all the options are correct.