Hot lava cools and forms new rock. Water vapor condenses to form a cloud. A seismic wave travels through the mantle. An ocean basin forms between two continents.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following processes usually takes the longest amount of time?
Possibilities:
- Hot lava cools and forms new rock.
- Water vapor condenses to form a cloud.
- A seismic wave travels through the mantle.
- An ocean basin forms between two continents.

An ocean basin forms between two continents.