Which discovery suggests extraterrestrial life may be constructed in a similar fashion to life on Earth?

• A. The laws of physics are the same everywhere.
• B. Water's abundance on Earth implies universal life.
• C. The chemical elements that make up life on Earth are common.
• D. The existence of carbon-based chemistry on Earth.

Answer: (C)

The idea being tested is that the same building blocks that make life on Earth possible are not rare in the universe. If the chemical elements that constitute life here are common elsewhere, then other worlds have the material to assemble similar biochemistry and life could be built in a familiar way.

The best choice says those life-building elements—like carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur—are common. That broad availability means the same kinds of organic molecules that form proteins, nucleic acids, and membranes could arise elsewhere, supporting Earth-like biochemistry and, potentially, life.

The other statements don’t directly support that connection. Simply knowing the laws of physics are the same everywhere doesn’t address whether life’s chemistry is feasible elsewhere. Assuming water is abundant here doesn’t guarantee life is universal. And carbon-based chemistry exists on Earth, but that alone doesn’t establish how widespread or similarly constructed life would be elsewhere.