This statement is true

The correct option is All of the above.

To understand why this is correct, let us analyze each statement individually:
1. Microtubules are composed of tubulins: Microtubules are hollow, cylindrical structures of the cytoskeleton. They are polymers assembled from heterodimers of α-tubulin and β-tubulin proteins. Therefore, this statement is true.
2. Microfilaments are composed of actin: Microfilaments, also known as actin filaments, are the thinnest filaments of the cytoskeleton. They are helical polymers made up of globular actin (G-actin) monomer subunits that assemble into filamentous actin (F-actin). Therefore, this statement is true.
3. Intermediate filaments are resistant to cytochalasin-B and colchicine: Cytochalasin-B is a drug that specifically inhibits the polymerization of actin microfilaments, while colchicine is a drug that binds to tubulin and prevents the polymerization of microtubules. Because intermediate filaments are chemically and structurally distinct from both microfilaments and microtubules, their assembly and stability are unaffected by these drugs. Thus, intermediate filaments are resistant to both cytochalasin-B and colchicine, making this statement true.

Since all three individual statements are correct, the correct choice is All of the above.