The crowd was large, so the speaker had to use a megaphone in order to be heard which of the following does the root Nega mean in megaphone does it mean miniature magnificent, huge or sound?

The root "Nega" does not have a specific meaning in English. It is likely a misspelling or a misinterpretation of the root "Mega," which means large or great. In the word "megaphone," the root "Mega" implies a large or powerful sound, extracted by amplifying the speaker's voice. Therefore, in the given context, the root "Mega" in "megaphone" would mean "sound."