The cook ___ the soup to check if it is salty enough.

The correct answer is "tastes". Explanation: In this sentence, we need to choose the correct tense of the verb "taste". The sentence is describing a general action or fact: a cook tastes soup regularly to see if it's salty enough. Therefore we should use the Simple Present tense which for "taste" in third person singular becomes "tastes". The "is tasting" would be used to describe a specific action in progress now, which doesn't fit the context of the sentence.