**The Cytoskeleton: an Overview**

The cytoskeleton is a complex network of protein filaments that provides structural support and enables various cellular processes in eukaryotic cells. It plays a crucial role in maintaining cell shape, facilitating cell division, enabling cell movement, and organizing cellular components.

**Proteinaceous Filaments: the Building Blocks of the Cytoskeleton**

The correct answer to the given question is option 'B': proteinaceous filaments. These filaments are the primary components of the cytoskeleton and are responsible for its structure and function. There are three main types of protein filaments that make up the cytoskeleton:

1. **Microfilaments (Actin Filaments):** These are the thinnest filaments and are composed of the protein actin. Microfilaments are involved in cell contraction, cell shape maintenance, cell division, and cell movement. They also form the core of microvilli and are responsible for muscle contraction.

2. **Intermediate Filaments:** These filaments have an intermediate diameter and are composed of various proteins, such as keratins, vimentin, and neurofilaments. Intermediate filaments provide mechanical strength and support to cells, especially in tissues subjected to mechanical stress, such as skin, hair, and nails.

3. **Microtubules:** These are the largest filaments and are composed of the protein tubulin. Microtubules play a crucial role in cell division, intracellular transport, and maintaining cell shape. They form the spindle fibers during mitosis and provide structural support to cilia and flagella.

**Other Components of the Cytoskeleton:**

While proteinaceous filaments are the main components of the cytoskeleton, there are other molecules and structures associated with it:

1. **Cellulose Microfibrils:** Cellulose microfibrils are not part of the cytoskeleton. They are long, straight chains of cellulose molecules that provide structural strength to plant cell walls. Cellulose is a complex carbohydrate and is not directly involved in the cytoskeletal architecture or cellular processes.

2. **Callose Deposit:** Callose is a polysaccharide that can accumulate in plant cell walls during certain developmental stages or in response to stress. It is not a component of the cytoskeleton and does not contribute to the structural integrity or functionality of the cytoskeleton.

3. **Calcium Carbonate Granules:** Calcium carbonate granules are also not part of the cytoskeleton. They are inorganic structures found in some organisms, such as marine animals, for skeletal support. Calcium carbonate does not play a role in the cytoskeletal architecture or cellular processes.

In conclusion, the cytoskeleton is primarily composed of proteinaceous filaments, including microfilaments, intermediate filaments, and microtubules. These filaments provide structural support, enable cell movement, and facilitate various cellular processes. Cellulose microfibrils, callose deposits, and calcium carbonate granules are not part of the cytoskeleton and have different functions in the cell.