Select the correct Active/Passive form of the given sentence. The tea…

The teacher told the students that the Greenhouse Effect is the way in which heat is trapped close to Earth’s surface by Greenhouse Gases.

The teacher told the students that the Greenhouse Effect was the way in which heat was trapped close to Earth’s surface by Greenhouse Gases.

The teacher told the students that the Greenhouse Effect had been the way in which heat is trapped close to Earth’s surface by Greenhouse Gases.

The teacher told the students that the Greenhouse Effect is the way in which heat was trapped close to Earth’s surface by Greenhouse Gases.