The T cells that limit the degree of immune system activation from a single stimulus are __________.

• A. cytotoxic T cells (CD8+)
• B. regulatory T cells (Tregs)
• C. helper T cells (CD4+)
• D. memory T cells

Answer: (B)

Verified step by step guidance

1. Understand the role of different T cell types in the immune system: Cytotoxic T cells (CD8+) kill infected cells, Helper T cells (CD4+) assist other immune cells, Memory T cells provide long-term immunity, and Regulatory T cells (Tregs) control immune responses.
2. Focus on the function of Regulatory T cells (Tregs), which are specialized in suppressing or limiting immune system activation to prevent excessive or autoimmune responses.
3. Recall that the question asks for the T cells that limit the degree of immune system activation from a single stimulus, which points to cells involved in immune regulation rather than activation or memory.
4. Match the function of limiting immune activation to Regulatory T cells (Tregs), as they maintain immune homeostasis and prevent overactivation.
5. Conclude that the correct answer is Regulatory T cells (Tregs) because they act as the immune system's 'brakes' to control the intensity of the immune response.