What role does the independent and dependent varibles play in a controlled experiment

List three reasons why explorers began to explore new, and old areas. [[ps: doesn't explicitly say where. i think it's more in general.

Ahistorian who compares the expansion of political systems to the expansion of economic systems is organizing history by o a. region b. culture c. period d. theme

Which behavior is appropriate in the laboratory? eating a snack while conducting an experiment mixing chemicals as instructed by the lab procedure tasting unknown chemicals to identify them tossing around a football with friends