It is one of those drills where you have to choose between some given words by clicking on them. The right answer is with "think" but "think" isn´t there. The only verb given to click on is "talk" so the answer is wrong but there is no way to give the right answer with the options available.
The default translation is actually "Two heads are better than one". Obviously, you should have been shown that instead of the version with "think" - especially if you weren't given that word tile - but Duolingo unfortunately isn't always smart enough to do so. :(