Compare the student text with the source.
Source: Russell Freedman, Who Was First?, page 15. Published by Clarion Books, 2007:
While Columbus was a courageous and enterprising mariner, he proved to be a poor governor, unable to control the greed of his followers.
Student text:
Columbus was a brave and adventurous sailor but turned out to be an ineffective leader.
Is the student text plagiarized?
No, it is not plagiarized.
Yes, because it fails to use quotation marks.
Yes, because it fails to cite the source.
Yes, because it fails to use quotation marks and fails to cite the source.