Question

1. how do supporting ideas reinforce the main idea?

they provide examples.
they suggest related topics.
they summarize the details.
they restate it.

Explanation:

Supporting ideas in writing or communication are meant to strengthen the main idea. Providing examples is a common and effective way to do this. For instance, if the main idea is that exercise is beneficial, giving examples like "Regular running improves cardiovascular health" or "Yoga enhances flexibility" reinforces the main idea. Suggesting related topics might go off - track from reinforcing the main idea. Summarizing details could be part of a conclusion but not the main way to reinforce. Restating the main idea is not the same as reinforcing it with evidence.

Answer:

They provide examples.