The answer here is D, and it's kind of obvious. But you probably already knew the answer and are just doing this for piece of mind.
Explanation: Just the fact that we don't know whether or not there even is extraterrestrial life rules out every other answer, without even needing to go in depth.
(Okay, I read your question completely wrong, it's asking for which one of these has been solved isn't it?)
This is tough because all of these other than D have been figured out. Go with the methane atmosphere then.
Answer:
A conversion error between two measurement systems
Explanation:
Exocrine glands are the name of the gland that transports secretions through ducts
Threatened is the definition used when describing a species at risk of extinction
Photograph the impression, frame the impression, pour the cast, remove the cast is the one that describes the correct order of steps to be taken when casting a soil impression. The correct option among all the options that are given in the question is the second option or option "B". Casting is a great method for preserving some kind of impression to be looked at in the future.
