Answer:
Element
Explanation:
All matter is made up of very small particles called atoms. Atoms are the building blocks of all matter. When a substance contains only one type of atom, it is called an element. ... <u>An element is a pure substance and is made of only one type of atom; it cannot be broken down into a simpler substance.</u>
What on earth, please repeat the question clearer
Well, on average 2/3 of a persons weight is water.
My Answer: Vestigial organs
Why?: " Vestigial organs are physical structures that were fully developed
and functional in an ancestral group of organisms but are reduced
and unused in the later species."
Hope I helped! :D