Correct Answer: thymus by lymphocytes

Solution : The correct option is thymus by lymphocytes.

The thymus is involved in the growth, and maturation of T lymphocytes (T cells), which are immune cells that play a key role in the immunological response. The thymus is where T cells mature, and are selected, ensuring that they can recognize, and respond to certain infections without destroying the body's tissues. T cells mature and circulate through the circulation, and lymphatic system, where they can play a variety of functions in the immune response, including assisting B cells in producing antibodies when necessary.