According to the tutorial, which is considered to be a serious breach of academic integrity? $($Choose the best answer$)$

Question $3$ options:

a$)$

Plagiarism $($passing off someone else's words or ideas as your own$)$

b$)$

Asking a friend to check your work

c$)$

Obtaining an old copy of a test

d$)$

Contract cheating: having someone else complete an entire assignment and submitting it as your own work