What contributions did Aristotle make during the Hellenistic era? Pick all the right answers.

He was the director of the library in Alexandria.

He said that reason was the key to learning.

He promoted the use of questions to help students learn.

He estimated Earth’s circumference using geometry.

He classified the names of many animals.

Two of these describe "federalism." (choose two answers) select one or more: a. the national government absolutely controls all state governments. b. power is shared by the national and state governments. c. state governments exercise absolute power over the national government. d. it is a compromise meant to eliminate the disadvantages of a "unitary" and a "confederate" system.