A community of plants and animals that live and interact together in a particular region is called an ecosystem.
A scientist who studies living things is called a biologist
Answer:Enrico must multiply the distance of mars from sun (meters) with the
to convert the distance in astronomical units.
Explanation:
1 astronomical unit = 

Let the distance between the sun and Mars be Y( meters)
Distance in AU= 
Enrico must multiply the distance of mars from sun (meters) with the
to convert the distance in astronomical units.
The answer is (B. levothyroxine)