Identify most suitable option.

What should be in a tree?

The logic followed is:

In botany, a tree is a perennial plant with an elongated stem, or trunk, roots, supporting branches, and leaves in most species.

As per the basic requirement for survival, the root is the most important part of the tree.

Option 1 - Flowers

Non-flowering plants are those that do not ever produce flowers. Some non-flowering plants, called gymnosperms, still produce seeds while others use spores for reproduction.

Option 2 - Horn

It is not always compulsory to be present in the tree.

Option 3 - Roots

More importantly, roots are the lifeline of a plant, taking up air, water, and nutrients from the soil and moving them up into the leaves, where they can interact with sunlight to produce sugars, flavors, and energy for the plant.

Option 4 - Fruit

There are many trees that don't bear any fruits in their lifetime.

Hence, the correct answer is "Roots".