1. Choice (c) is correct. The crust is the outer layer of the earth. Choice (a) is the core of the earth which consists of two parts, the inner and outer core, and is the hottest layer. Choice (b) is the mantle which is solid and rocky.
2. Choice (a) is correct. Image 4 is a plain. Plain is a wide and flat surface of the earth'ss crust where there are few trees standing and is ideal for planting crops, such as rice, corn, wheat, and barley.
3. Choice (d) is correct. Plate tectonics, volcanoes, and continental drift cause the crust's changes. The earth is consists of tectonic plates which slowly moves through time. Because of too much heat from the inmost part of the Earth, the earth's crust suffers from rupture which serves as a passage of magma, volcanic ashes, and gasses. Continental drift is a theory that once upon a time, the Earth has only one continent but with the passage of time, it drifted to where it is today.
4. Choice (b) is correct. Choice (a) happens in the mantle and is moving very slowly because of convection currents. Choice (c) is a movement of plate tectonics in a sideward or downward pattern from the edge of the crust to the mantle. Choice (d) happens after the process of subduction, wherein one plate tectonics may be under the other, and materials above the plates are added.
5. Choice (b) is correct. The layer that separates the crust and outer core is the mantle which is rocky and behaves solidly but as time passes by, it becomes fluid.
6. Choice (d) is correct. Image 1 is a hill. Hills have rounded summit and usually not steep. On the other hand, mountains are land formations that usually have distinct summits, sometimes cone-shaped, and obviously steeper than hills.