What type of cells are known to carry out the actions of cell mediated immunity?

Cytotoxic T-cells are the primary cells responsible for executing cell-mediated immunity. This adaptive immune response involves the direct attack on infected or cancerous cells. Once activated by recognizing specific antigens presented by Major Histocompatibility Complex (MHC) molecules on the surface of these cells, cytotoxic T-cells proliferate and differentiate into effector cells. These effector cells are capable of recognizing and binding to infected cells, leading to their destruction through mechanisms such as inducing apoptosis (programmed cell death).

While helper T-cells play a crucial role in coordinating the immune response and activating other immune cells, they do not directly kill infected cells. Memory B-cells, on the other hand, are involved in the humoral response by producing antibodies and lack the engagement that is characteristic of cell-mediated immunity. Regulatory T-cells function to modulate and suppress the immune response to maintain homeostasis and tolerance, rather than directly attacking infected cells. Therefore, cytotoxic T-cells are essential for the specific actions involved in cell-mediated immunity, making them the correct answer to this question.