Which of the following best describes a cytotoxic T-cell?

A cytotoxic T-cell, also known as a CD8+ T-cell, plays a crucial role in the adaptive immune system. Its primary function is to recognize and eliminate cells that have been infected by viruses or have become cancerous. These cells can directly kill target cells by releasing cytotoxic granules that contain perforin and granzymes. Perforin forms pores in the target cell membrane, allowing granzymes to enter and induce apoptosis, or programmed cell death, in the infected or transformed cells.

The other options describe different immune cells or functions. For example, helper T-cells assist other immune cells, B-cells produce antibodies, and antigen-presenting cells, such as dendritic cells and macrophages, display antigens to T-cells to initiate an immune response. Each of these functions is important for a comprehensive immune response, but they do not describe the specific role of cytotoxic T-cells in killing infected or cancerous cells.