Luke seems to indicate that Elizabeth knew the answer to her question. She said that as soon as she heard with her ears the sound of Mary’s greeting (ἰδοὺ γὰρ ὡς ἐγένετο ἡ φωνὴ τοῦ ἀσπασμοῦ σου εἰς τὰ ὦτά μου), the child or baby in her womb leapt or jumped for joy or exultation (ἐσκίρτησεν ἐν ἀγαλλιάσει τὸ βρέφος ἐν τῇ κοιλίᾳ μου). This was a repetition of what was said in verse 41, except that Elizabeth said it here. John knew Jesus from the very beginning of his existence.
There was no mention of the prophet Jeremiah in 2 Kings at all, which has led many to speculate about his existence. Obviously this book has a lot to say about Jeremiah. King Nebuchadnezzar liked Jeremiah because he had constantly told the Judean king and others to serve the king of Babylon. Thus the Babylonian king told the captain of his guard Nebuzaradan to care for Jeremiah and not hurt him. In fact, Nebuzaradan was to do whatever Jeremiah asked him to do. Thus Jeremiah may have been a traitor to Judah as a collaborator with the king of Babylon.