Which part of the sentence is a prepositional phrase

(1) fire extended humans’ geographical boundaries by allowing them to travel into regions that were previously too cold to explore. (2) it also kept predators away, allowing early humans to sleep securely. (3) fire, in fact, has been a significant factor in human development and progress in many ways. (4) other obvious benefits of fire are its uses in cooking and in hunting. (5) probably even more important, however, is that learning to control fire allowed people to change the very rhythm of their lives. (6) before fire, the human daily cycle coincided with the rising and setting of the sun. (7) with fire, though, humans gained time to think and talk about the day’s events and to prepare strategies for coping with tomorrow. the sentence that expresses the main idea is: (type the number of the sentence. then click “go.”)

Plz me (a) assignment how-to essay submit your essay, illustrated with at least one visual. review your how-to essay, and make sure you've met the following requirements: describe a process or procedure using specific information. describe each step clearly. use second-person point of view. include all materials and steps needed for the task. include a minimum of one visual that demonstrates or supports your procedure. use chronological order and transitions that lead readers through the sequence. use language and tone appropriate for the audience. use complete sentences and correct capitalization, punctuation, and spelling. use spell and grammar check functions before submitting your draft. ill get my own picture just right every ting down

The purpose of an informative essay is to express personal feelings about a topic. describe events from a certain point of view. instruct the reader about a topic. express and defend an opinion.