Which language are you creating a course in? This is the "other" topic, which isn't well set up for creating lists in any particular language - it is more from trying things out, and learning miscellaneous facts etc.
In a language topic the system is set up to look for synonyms and to mark either answer correct, but to play the audio from the expected answer, so as to reinforce that meaning. Does that make sense? Let me know if I can do anything to help,