Mango : Fruit :: Potato : ?

The correct answer is A. Root.

A mango is a fruit, while a potato is a root vegetable. Fruits are the sweet, fleshy part of a plant that contains the seeds. They are typically eaten raw, but can also be cooked. Root vegetables are the edible parts of plants that grow underground. They are typically cooked, but can also be eaten raw.

Option B, stem, is incorrect because a stem is the part of a plant that supports the leaves and flowers. Option C, flower, is incorrect because a flower is the reproductive part of a plant. Option D, fruit, is incorrect because a potato is not a fruit.