The right answer is B.
Insulin is a hormone naturally secreted by the pancreas, specifically by specialized cells located in the islets of Langerhans. It allows glucose (sugar) to pass blood into the cells of the body. These will use glucose as energy or store it for future use.
In healthy subjects, insulin is secreted continuously. The body produces insulin according to the needs and foods consumed. For example, after a meal, the pancreas secretes additional insulin, allowing blood glucose to stay within normal limits.