The correct answer is A. Skillful.
The word “skillful” means having or showing a high level of skill. It is derived from the word “skill,” which means the ability to do something well. The word “skillful” is spelled with one “l” and one “f.”
The other options are incorrect because they are not spelled correctly. The word “skillfull” has two “l”s, the word “Skiilful” has two “i”s, and the word “Skilfull” has two “f”s.
It is important to spell words correctly in order to be understood clearly. When words are spelled incorrectly, it can be difficult to understand what the writer is trying to say. This can lead to misunderstandings and confusion.