Option B)Vacuole is membrane-bound(i.e. it is covered by single membrane called Tonoplast) & contains water & excretory substances....Do refer cell:structure & functions chapter in Ncert....

Vacuole in a plant cell

Introduction: Plant cells have a unique structure that makes them different from animal cells. One of the distinguishing features of a plant cell is the presence of a large central vacuole. Vacuoles are membrane-bound organelles that play an important role in the life of a plant cell.

Types of Vacuoles: There are two types of vacuoles in a plant cell: a tonoplast-bound central vacuole and small, specialized vacuoles.

1. A tonoplast-bound central vacuole:
This is the largest and most important vacuole in a plant cell. It occupies almost 80% of the total volume of the cell. The central vacuole is surrounded by a tonoplast, which is a single membrane that separates the contents of the vacuole from the cytoplasm.

2. Small, specialized vacuoles:
These are smaller vacuoles that are found throughout the plant cell. They have a specific function and are often found in specific cell types.

Function of Vacuoles: The vacuole has several important functions in a plant cell. Some of these functions include:

1. Storage:
The central vacuole stores various substances such as water, nutrients, waste products, and pigments. This is important for the growth and survival of the plant.

2. Turgor Pressure:
The central vacuole helps maintain the turgor pressure of the plant cell. Turgor pressure is the pressure that is exerted by the contents of the cell against the cell wall. This pressure helps the plant maintain its shape and structure.

3. Excretion:
The vacuole also helps in the excretion of waste products from the plant cell. These waste products are stored in the vacuole until they can be safely expelled from the cell.

4. Defense:
The vacuole can also play a role in defense. Some vacuoles contain toxic substances that can deter herbivores and other predators.

Conclusion: In conclusion, the vacuole is an important organelle in a plant cell. It has several important functions that are necessary for the growth and survival of the plant.