Which of the following is both an exocrine and endocrine gland?

Match the types of cells listed under column $I$ with the secretions given under column $II$. Choose the answer which gives the correct combination of the alphabets of the two columns.

Column $-I$ (Types of cells)	Column $-II$ (Secretions)
$(A)$ Beta cells	$(p)$ Lysozyme
$(B)$ Mast cells	$(q)$ Histamine
$(C)$ Paneth cells	$(p)$ Lysozyme
$(D)$ Acinar cells	$(s)$ Pancreatic enzymes

Diabetes mellitus is caused due to the deficiency of insulin, which is secreted by:

The element present in traces in insulin is:

Islets of Langerhans are present in

Give a reason: Pancreas is an endocrine as well as an exocrine gland.