Answer:
1-A: A cataract is another term for waterfall
2-E: Ex. European countries colonized North and South America centuries ago
3-F: Escarpment is a word for a steep cliff or slope
4-B: A topographic map shows the geographic features of an area
5-D: A tributary is a smaller stream that always flows into a bigger one
6-C: Veldt is another word for a plateau
Answer: Plato is an author of "dialogues" (The Republic, Laws etc etc.) where the main character is Socrates. Socrates is a philosopher who uses a special kind of dialogue (so-called dialectic dialogue or dialectic method) which leads him to the truth. In other words he follows LOGOS who leads him to uncovering the Truth.
Explanation: Greek word ALETHEIA means "disclosure" and "truth" at the same time. It means that truth is always hidden. Much older Greek philosopher (pre-Socratic) Heraclitus had a dictum: "Truth likes to hide"....it seems that Socrates/Plato followed this thesis.
The area referred to in the question is missing but taking into account the area of the world as a whole, the answer would be A)Atlantic and Pacific.