Planet X is a terrestrial planet in our solar system. It has 21% oxygen in its atmosphere. Humans can walk on this planet without the aid of a space suit.
Based on the description, planet X is
.

Question

Planet X is a terrestrial planet in our solar system. It has 21% oxygen in its atmosphere. Humans can walk on this planet without the aid of a space suit.
Based on the description, planet X is 
.

Downpour17 · Answer

Describe "Planet X" In your own terms and review some other answers you may have came up with

563blackghost · Answer

habitable i would assume, i mean if we can walk without a suit we could practically live on that planet if everything else helps with the human race to live there.

Mercury · Answer

answer choices: 
earth
mars
mercury
venus

"humans can walk on this planet without the aid of a space suit" is the major clue that immediately narrows us down to Earth as the only planet with an atmosphere that humans are adapted to breathe/live in without a suit