Are you sure you have cleaned the kitchen? There is still a pretty ____________ smell coming from it.

The correct answer is "unpleasant," which fits perfectly in the context of the sentence. The sentence discusses a smell coming from the kitchen, and based on the use of the word "still," it implies that the smell is not desirable. The word "unpleasant" directly describes a negative quality of the smell, indicating that it is not enjoyable or agreeable.

In contrast, "pleasant" would suggest a positive smell, which would contradict the implied meaning. "Pleasing" is an adjective that can sometimes refer to something that provides satisfaction or enjoyment, but when describing a smell, it doesn't work as well in this context. "Pleased," on the other hand, is an adjective used to express satisfaction or happiness about something, usually relating to a person's feelings rather than describing a smell.

Thus, "unpleasant" is the most suitable choice, effectively conveying the negative impression of the smell in question.