سوال ۱ کنکور ارشد مهندسی مکانیک ۱۴۰۵

A source of information is where information comes from — the standard collocation "a (good/reliable) source of information." The sentence warns that Instagram is not a good place to get medical and health-related information, so "source" fits perfectly. discovery (finding something new), cause (what makes something happen), and agreement (mutual accord) do not collocate with "of information" here nor match the meaning.