Which of the following is a stem?

The correct answer is (d). Sweet potato is a stem.

A stem is the part of a plant that supports the leaves, flowers, and fruit. It also transports water and nutrients from the roots to the leaves, and food from the leaves to the rest of the plant.

Turnip, ginger, and carrot are all roots. Roots anchor the plant in the soil and absorb water and nutrients from the soil.

Sweet potatoes are a type of root vegetable that is native to Central and South America. They are a good source of vitamins A and C, as well as dietary fiber. Sweet potatoes can be eaten cooked or raw, and they are a popular ingredient in many dishes.