Answer:
D. Exposure to infectious agents
Step-by-step explanation:
The exact cause of type 1 diabetes is unknown. Usually, the body's own immune system — which normally fights harmful bacteria and viruses — mistakenly destroys the insulin-producing (islet, or islets of Langerhans) cells in the pancreas. Other possible causes include:
Exposure to viruses and other environmental factors
Family history. Anyone with a parent or sibling with type 1 diabetes has a slightly increased risk of developing the condition.
Genetics. The presence of certain genes indicates an increased risk of developing type 1 diabetes.
Geography. ...
Age.