4. Tectonic plates are part of the * upper mantle continental and oceanic crust lower mantle continental crust only

**Answer:** *Continental and oceanic crust* **Explanation:** Tectonic plates are large, rigid pieces of the Earth's lithosphere that move over the semi-fluid asthenosphere beneath them. Each tectonic plate is composed of two main parts: 1. **Continental Crust:** This is the thicker, less dense part of the plate that forms the continents. 2. **Oceanic Crust:** This is the thinner, denser part that forms the ocean floors. While the tectonic plates do include the uppermost part of the mantle (often referred to as the *upper mantle* or the lithospheric mantle), among the options provided, "*continental and oceanic crust*" best represents the primary components of tectonic plates. **Correct Option:** • **Continental and oceanic crust**