Final answer:
Superficial ulcers of the skin caused by repeated cold exposure are called chilblains. They are distinct from frostbite, trench foot, and general lesions.
Step-by-step explanation:
Superficial ulcers of the skin that occur when an individual is repeatedly exposed to the cold are called chilblains (Answer D). Frostbite (Answer A) refers to injury of the skin and underlying tissues resulting from prolonged exposure to freezing temperatures, which is not characterized by superficial ulcers but by more severe tissue damage. Trench foot (Answer B) occurs due to prolonged exposure to damp, unsanitary, and cold conditions but does not typically result in superficial ulcers. Lesions (Answer C) is a general term that refers to an area of abnormal tissue or injury, which does not specifically account for the cold-induced condition being described.