Which of the following is not a component of the disease tetrahedron?

Control agent is not a component of the disease tetrahedron.
A disease pyramid or tetrahedron, allows for the addition of a fourth causal factor of disease. Humans factor into the disease triangle because the influence of human activity on disease is pervasive in agriculture.
The concept of a disease pyramid or tetrahedron is composed of four main components that are environment, pathogen, host and host microbiome. The control agent is not a component of this tetrahedron.