Name the following:
The undigested cellulose which is fibrous in nature.

Explanation

**Step-by-Step Solution:**

1. **Identify the Key Terms**: The question asks for a term that describes "undigested cellulose" which is "fibrous in nature".

2. **Understand the Concept of Cellulose**: Cellulose is a complex carbohydrate that is found in the cell walls of plants. It is not digestible by humans but plays an important role in the diet.

3. **Define the Role of Undigested Cellulose**: Although cellulose is not digested, it is important for digestive health. It helps in the movement of food through the digestive tract and aids in the elimination of waste.

...