Scientists have found fossils of tropical plants in Antarctica. How could tropical plants have grown in Antarctica? At one time, Antarctica was located closer to the equator.

At one time Earth's entire surface was a tropical rainforest.

Catastrophic volcanic eruptions melted the ice and exposed the soil to sunlight.

The rotation of the Earth has increased, causing cooling of the atmosphere.

Johnny is measuring how long it takes for new crust to form in the Mid-Atlantic Ridge versus the Great Rift Valley. What is the independent variable?

how long it takes for new crust to form

the amount of new crust formed

the Mid-Atlantic Ridge and the Great Rift Valley

Johnny repeating the experiment twice

need asap if your answer is random you will be reported