Antibodies are secreted by:

The correct option is B-Cells.

Step-by-Step Explanation:

1. Understanding the Immune System Cells:
The adaptive immune system is primarily composed of white blood cells known as lymphocytes, which include T-lymphocytes (T-cells) and B-lymphocytes (B-cells). Each of these cells plays a distinct role in defending the body against pathogens.

2. Role of B-Cells:
B-cells are responsible for humoral immunity (antibody-mediated immunity). When a B-cell encounters its matching antigen, it becomes activated and differentiates into plasma cells. These plasma cells act as factories that produce and secrete large quantities of proteins called antibodies (immunoglobulins). The secreted antibodies circulate in the blood and lymph, binding to specific antigens to neutralize them or mark them for destruction by other immune cells.

3. Comparison with other options:
- T-Cells: These cells are involved in cell-mediated immunity. They do not secrete antibodies. Instead, they directly destroy infected host cells (cytotoxic T-cells) or help activate other immune cells (helper T-cells).
- α-Cells (Alpha cells): These are endocrine cells located in the islets of Langerhans in the pancreas, responsible for secreting the hormone glucagon.
- β-Cells (Beta cells): These are also endocrine cells in the pancreatic islets of Langerhans, responsible for secreting the hormone insulin.

Therefore, B-cells are the specific cells responsible for the secretion of antibodies.