I am pretty sure it would be massive because it is an English question. If you are doing a multiple choice question you should see which one fits the best. If could also be positive impact.
The girls found a Dead body
It might be clearer to say: According to the dictionary, a squawk is not the same thing as a squeak. there's no need for them to be plural in your sentence and it's likely that, in the dictionary, they're listed as "squeak" and "squawk" singularly. when describing dictionary definitions it's best to use the form of the word that the dictionary uses for clarity.
because, it is easier to use plants or things of that type other than using human trials which can be lethal if done wrong.