Final answer:
The term for a basaltic lava flow with a smooth, ropy appearance is pahoehoe, which is distinct from the rough-surfaced a'a', the pyroclastic ignimbrite, and the light, vesicular pumice.
Step-by-step explanation:
The textural term for a basaltic lava flow that has a smooth, ropy appearance is pahoehoe. This type of lava flow is characterized by its smooth, billowy, or ropy surface, which is formed as the lava cools and solidifies while still in motion. In contrast, a'a' refers to a basaltic lava flow with a rough, jagged, and clinkery surface.
The other options provided, ignimbrite and pumice, represent different volcanic materials: ignimbrite is a type of pyroclastic flow deposit, and pumice is a vesicular volcanic rock that is light enough to float in water.