Questions: We still have no proof that life can exist on other planets. Kepler-160e is the best candidate for an Earth-like planet. Most exoplanets have been found orbiting red dwarf stars. A planet's surface must have liquid water for life to exist.

The answer is the first one: We still have no proof that life can exist on other planets.

Explanation for each option:

1. We still have no proof that life can exist on other planets.

   • This statement is correct. As of now, while there is significant research and exploration aimed at finding life beyond Earth, there is no definitive proof that life exists on other planets.

2. Kepler-160e is the best candidate for an Earth-like planet.

   • This statement is incorrect. While Kepler-160e might be a candidate for an Earth-like planet, there are other exoplanets, such as those in the TRAPPIST-1 system or Proxima Centauri b, that are often highlighted as strong candidates for Earth-like conditions.

3. Most exoplanets have been found orbiting red dwarf stars.

   • This statement is correct. Red dwarf stars are the most common type of star in the Milky Way galaxy, and many exoplanets have been discovered orbiting them due to their abundance and the fact that their smaller size makes it easier to detect planets.

4. A planet's surface must have liquid water for life to exist.

   • This statement is not necessarily correct. While liquid water is considered a key ingredient for life as we know it, it is not a definitive requirement for all forms of life, especially considering the potential for life forms with different biochemistries.

In summary, the most accurate statement given the current state of scientific knowledge is that we still have no proof that life can exist on other planets.