Which of the following BEST describes protists?
A. They are all parasites.
B. They are all free-living.
C. They all live in colonies.
D. They can be parasites, free-living, or colonial.

i would say it is

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.