It is technically a fruit.
No, the physical tomato is a fruit that grows on a talk (stem).
A young tomato plant and an adult tomato plant both have a stem.
stem
Both. Since it is a member of the plant kingdom, the tomato is a plant. Like wisteria the tomato grows as a vine, but usually bushes. Some tomato plants, however, are meant to vine along the ground, and all tomato plants will root anywhere the stem is close to dirt.
Tap root
A tomato is the developed ovary of the tomato plant flower. The plant is called a tomato plant and the fruit is the tomato you buy in the fruit shop.
Carrot is a root vegetable.
Capsicum is a fruit that grows from the flower of the capsicum plant. It is not a root or a stem.
root
tomato is a fruit.
Tap root
An onion, strictly speaking, is a 'bulb' and is a stem.