Introduction:
Silkworms are the larvae of silk moths, specifically the Bombyx mori species. They are known for their ability to produce silk, which is spun into cocoons. Silkworms have specific dietary requirements and primarily feed on the leaves of certain plants. Among the options given, the correct answer is option 'B' – Mulberry.

Explanation:
Silkworms have a strong affinity for the leaves of the mulberry tree. The mulberry tree (Morus spp.) is the primary food source for silkworms in their larval stage. Here's why:

1. Nutritional Requirements:
- Silkworms require a diet that is high in protein, carbohydrates, and vitamins.
- Mulberry leaves are rich in these nutrients, making them an ideal food source for silkworms.
- The leaves contain essential amino acids, which are necessary for the growth and development of silkworms.

2. Digestive System Adaptation:
- Silkworms have a specialized digestive system that allows them to efficiently digest mulberry leaves.
- They have an enzyme called "amylase," which helps break down the complex carbohydrates present in the leaves into simpler forms for digestion.
- This adaptation ensures that silkworms can extract the maximum nutritional value from mulberry leaves.

3. Mulberry Leaf Preference:
- Silkworms have a natural preference for mulberry leaves due to their taste and texture.
- The chemical composition of mulberry leaves, including their aroma and flavor, attracts silkworms and stimulates their feeding behavior.
- This preference has been cultivated over centuries of domestication, as mulberry trees were specifically grown to support the silk industry.

Conclusion:
In conclusion, silkworms feed on the leaves of the mulberry tree. Mulberry leaves provide the necessary nutrients for the growth and development of silkworms. Silkworms have a specialized digestive system that allows them to efficiently digest the leaves. Their preference for mulberry leaves is a result of their chemical composition and centuries of selective breeding.