F is the symbol for fluorine which is a single atom. A molecule is two or more atoms together, which makes F not a molecule.
The statement '(a) there are billions of galaxies in a galaxy cluster' accurately describes a relationship between two parts of the universe.
<h3>What is the solar system?</h3>
The solar system can be defined as a group of billions of galaxies that form a cluster due to gravitational forces that maintain all these celestial bodies linked together. This system contain our Sun.
In conclusion, the statement '(a) there are billions of galaxies in a galaxy cluster' accurately describes a relationship between two parts of the universe.
Learn more about galaxy clusters here:
brainly.com/question/955851
#SPJ1

Last option: Preserve an ecosystem

• The establishment of a bird reservation is a way to preserve an ecosystem because reservation provides suitable environment to organism. A healthy ecosystem means large number of biodiversity.
I believe the answer is C.
because when the dinosaurs thrived they ate most of the mammals which were small animals but when the dinosaurs went extinct the mammals grew larger in size and started to thrive.
Explanation:
In a freshwater aquatic ecosystem like a pond, the organisms in the food chain include algae, small animals, insects and their larvae, small fish, big fish and a fish-eating bird or animal
pls mark brainliest