The term "artifact" generally refers to an object made or used by humans. In a broader context, artifacts can encompass a variety of items, including tools, pottery, and artwork created by people. The other descriptions you provided can relate to different types of cultural or historical findings, such as fossils (imprint of a plant), human remains (remains of a person from long ago), or tablets and manuscripts (a written record of an early society), but these would not typically be classified as artifacts.
So, the correct answer from your list describing an artifact is "an object made or used by humans."