Which Rocks term is correctly associated with common use or association: “common in oceanic crust and lava plateaus”, and also with “an extrusive igneous rock”?

Correct Answer: Option D — Basalt. Basalt is correct because it is common in oceanic crust and lava plateaus. Basalt is also associated with an extrusive igneous rock. A further identifying fact is that Basalt is dark-coloured and fine-grained. Another useful fact is that Basalt is associated with common in oceanic crust and lava plateaus. Why the other options are incorrect: Option A — Pumice: It is used as an abrasive and lightweight aggregate and is associated with a vesicular volcanic rock; those are the identifying facts of Pumice. Option B — Obsidian: It is historically used for sharp cutting tools and is associated with a volcanic glass; those are the identifying facts of Obsidian. Option C — Sandstone: It is commonly used as a building stone and is associated with a clastic sedimentary rock; those are the identifying facts of Sandstone. Exam Takeaway: Link Basalt with “common in oceanic crust and lava plateaus” and “an extrusive igneous rock” for quick revision.