<em>no it is not a complete sentence because complete sentence requires a verb and a subject..
this sentence has a verb but not a subject so it is incomplete.....</em>
Answer:
Primary sources are documents, images or artifacts that provide firsthand testimony or direct evidence concerning an historical topic under research investigation. ... The same document, or other piece of evidence, may be a primary source in one investigation and secondary in another.
I'm not entirely sure about the options, but try one with an example or a question.