The answer is C or B.
If it was permeable water and other substances could get through.
And hard? That is one of those answer choices teachers throw in to try and make an obvious elimination choice.
I hope I have helped!
Https://www.studyblue.com/notes/note/n/test-2/deck/16537854 this should help
An object is in motion if its distance relative to another object is changing. To tell if an object is moving, you use a reference point. If an object's distance from another object [reference point] is changing. A place or object used for comparison to determine if something is in motion.
I'm not too sure if this is what you needed go know, I hope it helped
Protons: positive
neutrons: no charge
electrons: negative
This is an example of vestigial structure.
Vestigial structures are structures (cells, tissues and organs) found in an organism that has lost most or all of its primitive function through evolution. The vestigial structure has performed vital functions in the organism in the past but as there are changes in species as a result of natural selection, the structure became less important until it no longer functions. A reduced nonfunctional digit on the paws of dogs known as a dewclaw is an example of vestigial structure.