The correct answer is C. Students
Step-by-step explanation:
An idea web is a type of graph mainly used to show ideas or concepts that are connected especially with the purpose of generating ideas or brainstorming or recognizing the connection between ideas. Because of this, idea webs can link ideas that belong to multiple levels following a complex structure or as in the graphic presented link ideas that are related to one concept or main idea, which implies all ideas should be similar or belong to the same category.
In the example presented the main idea or central idea that works as a base for other ideas is "Who benefits from volunteer work?", this central idea implies, the ideas that connect to this should be groups of people or people that benefit from volunteer this is the case of the ideas already included "Children", "The elderly" and "The homeless". Considering this, the idea that best completes the web is "Students", because this idea also expresses a group of people like the rest of the ideas and because students benefit from volunteer work mainly because they can contribute to the society and learn in the process.