The only choice given to click on from the words provided were "Let" and " 's" to make the contraction "Let's". So I chose that, and it should be correct, as that is what the contraction "Let's" means = "Let us." BUT the answer said there was 'a typo"; that it had to be "Let us." "Us" is not offered in the boxes to click on. I hope this will be corrected, even though my answer was not marked wrong but merely "as a typo."