Read the sentences. East Antarctica is covered by massive layers of ice. The ice is thousands of meters thick. Which revision combines the sentence using a subordinating clause and subordinating conjunction?
East Antarctica, covered by massive layers of ice, is thousands of meters thick.
East Antarctica covered by massive layers of ice, which is thousands of meters thick.
East Antarctica is covered by massive layers of ice, which is thousands of meters thick.
East Antarctica is covered by massive layers of ice thousands of meters thick.