Please can someone help me with this question. I don’t understand at all

Identify the following group of words as an incomplete or complete sentence. if the sentence is incomplete, identify the reason. dinosaurs have disappeared a. complete sentence b. incomplete sentence: no subject c. incomplete sentence: subordinate clause d. incomplete sentence: no verb

(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.”)

Ineed ideas for this essay something easy that i can do does anyone have any ideas on what i should write on for this 100 points ! write a procedural essay with media that is 1 ½–2 pages in length. clearly state your topic, and include all steps necessary to complete the procedure. you will submit your prewriting and planning documents along with your essay. need i only have 4 hours to do this