What does it mean when an organism is "selected" in the process of natural selection?

Explanation:

. Natural selection is a pressure that causes groups of organisms to change over time. Animals inherit their genetics from their parents or ancestors, and the environment is constantly changing. So, no organism is perfectly adapted to its environment.

prism b but im not for sure

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds