SAT English Practice Question

A scientist is writing about the origins of Earth's oceans. The scientist wants to include a sentence that describes the chemical composition of early oceans. Which of the following sentences would best accomplish this?

1. A.The early oceans were thought to be much more acidic than the oceans are today, and the water would have been much warmer.
2. B.The early oceans contained a mixture of dissolved gases, including methane, ammonia, and hydrogen sulfide.
3. C.The early oceans were very salty, and there were very few life forms in them.
4. D.The early oceans were likely formed from the water that was released when comets and asteroids collided with Earth.