Step 1: Citrus fruits include lemon, orange, mosambi and grapefruit, all known for their sour taste.
Step 2: The sour taste comes largely from citric acid, and these fruits are also rich in ascorbic acid, which is the chemical name for Vitamin C.
Step 3: Citrus fruits are a well known natural source of Vitamin C, which helps the body build collagen, heal wounds and fight infections. A long term lack of this vitamin causes scurvy.
So the vitamin found abundantly in citrus fruits is Vitamin C. The correct answer is option C.