Which must mean almost the same as believed?

What are the choices? Could be Convinced, or Trust. Could answer correctly if you had the choices.

I'm not sure what your choices are, but here are some synonyms and phrases that me the same as Believed:

accept, admit, conclude, consider, have, hold, regard, suppose, think, trust, understand, accredit, affirm, buy, conceive, credit, deem, posit, postulate, presuppose, swallow, attach weight to, be certain of, be convinced of, be credulous, be of the opinion, count on, fall for, give credence to, have faith in, have no doubt, keep the faith, lap up, place confidence in, presume true, reckon on, rest assured, swear by,take as gospel, take at one's word, take for granted, take it

Hope This Helps!!!

-AnimeDabGirl

explanation: the line "to save the day, harry must get past a scary three-headed guard dog" from the summary best justifies the conclusion that harry potter and the sorcerer’s stone was influenced by ancient greek mythological literature. the three other choices had nothing to do with ancient greek literature - and the words "three-headed guard dog" are what makes that choice the correct answer.