A. intentional plagiarism
When something is done knowingly, the person doing it is intentional. The student mean to use the author's words without giving credit and knowing that by not giving credit, he/she was plagiarizing. This is the important part about intent. The person has to have purposefully done what they did and usually understand that it is wrong before the act had been done. In this sentence, "intentional plagiarism" is the correct answer.