The nerve connects to the heart and adjusts its speed according to the body's demands.
pulmonary
aortic
vagus
capillary

The answer is Vagus nerve. The vagus nerve is also known as the pneumogastric nerve,which is the tenth cranial nerve, and interfaces with parasympathetic control of the heart, lungs, and digestive tract. Where as there in no pulmonary nerve or aortic nerve or capillary nerve. Pulmonary and Aortic comes under plexus(a branch network of vessels or nerves). Capillary refers to the vessel.

Bis the