Scientists study salamanders and their ability to regenerate lost legs and tails. What additional information is essential for scientists to understand in order to apply this ability to humans who have lost limbs? how quickly the body parts regenerate
how similar salamanders are to humans
which body parts are most often lost
which genes control regeneration

The answer could be:

(/) which genes control regeneration

(/) how similar salamanders are to humans

(x) how quickly the body parts regenerate  (salamanders' size and form does not equate to human beings)

(x) which body parts are most often lost  (it was already given that it's legs and limbs)

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

population. population is the number of people or animals in a particular place. an example of population is over eight million people living in new york city.

here is your answer hope i .