I got this question twice in this lesson. Also the 'Julia eats with a spoon' one. I'm not sure if that's a bug.
Cammac is a masculine noun. You don't pluralise masculine nouns with -eñ. The plural of cammac is cammac.
Sorry, wrong comment. LOL I had to edit.
When you see these mistakes, please report them. This is why beta exists, to find these quirks and get them corrected.