What type of enzyme digests protein: amylase, lipase or protease?

The key to being able to answer this question is having good memory tricks in place.

In this case, connecting lipase with lipid in your mind will help you recall that lipases digest fats and so that cannot be the correct answer to this question.

Protease, by virtue of the 'prote' part of its name, can easily be connected with protein and thus is the correct answer to the question.

(By elimination, this leaves amylase as being the type of enzyme which digests sugars)