A person with severe combined immunodeficiency has no 1 Interferon
2 Interleukin
3 Histamine
4 Complement

Need not to answer if u don't know
Answer with full explanation.

I think it's interferon.

Explanation:

Interferons are substances produced by cells in the body to help fight infections and tumors. So, it would make sense if they don't have interferon, with severe combined immunodeficiency.

correct answer: understand the different control methods available

integrated pest management is an strategy that is based on the ecosystem and try to prevent the pest and the damage caused by them by applying combination of technique like habitat manipulation, biological control and use of resistant varieties.

the main aim of the integrated pest management is not to completely eliminate the pest but to strengthen the ecosystem so that conditions are favorable for plants and unfavorable for pests.