This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Helper cells belong to? \nSelect and explain. \nA. T cells, B. Macrophages, C. B cells, D. Monocytes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The category of effector T cell is a broad one that includes various T cell types that actively respond to a stimulus, such as co-stimulation. This includes helper, killer, regulatory, and potentially other T cell types. Reff: Ananthanarayanan & panikers textbook of microbiology 9th edition pg:135', 'role': 'assistant'}]