Read this entry from an online thesaurus and the sentence that follows.

whisper v. speak in a soft, low voice. synonyms: murmur, mutter, mumble, rustle.
usage notes: mutter and mumble have negative connotations; murmur has positive connotations.
rustle is used when something makes a sound other than speech that resembles a whisper,
as when the wind blows through leaves.

i saw elena smile and something to her baby, but i could not tell what she was saying.

using information in the thesaurus entry, choose the word that best completes the sentence.

There are actually several was that you fcould phrase this sentence.

You could say:

I saw Elena smile and whisper something to her baby, but I could not tell what she was saying.

I saw Elena smile and murmur something to her baby, but I could not tell what it was.

You could use most of the synonyms that go along with the word whisper, but be careful so that you're sentence still makes sense and in grammatically correct, dependent on where you place these verbs.

he does not belive what the men tell him about the jungle

answer: my favorite subject is choir

explanation: it is choir becuase you can sing and have fun singing at the same time with your friends.