I think the answer is D. ( or supported by observations ). Because theories change over time, they both NEED to be proven, they do NOT go off of consensus, but they do NEED to be supported by observations.
I hope this helps.
Solid because it maintains their shape and is rigid
in this case the answer would be letter "D"
Hi!!
The answer is <span>They regulate water intake and excretion.
Hope this helps!
-Payshence xoxo</span>