Final answer:
CD4+CD25+ regulatory T cells (Treg cells) inhibit various immune responses, including those against self-epitopes and epitopes related to infectious agents and tumors, preventing overactivation of the immune system.
Step-by-step explanation:
The cells that inhibit various immune responses against self-epitopes, as well as some responses against epitopes associated with infectious agents and tumors, are c) CD4+CD25+ regulatory T cells (Treg cells). These cells, sometimes referred to as suppressor T cells, bear the molecules CD25 and FOXP3 in addition to CD4. Their role is crucial for maintaining immune homeostasis and tolerance as they help to prevent overactivation of the immune system, which could lead to autoimmune diseases and other medical issues. Treg cells function by suppressing the immune responses of other cells, including T cells and B cells.