Usually the hook at the beginning or the thesis at the end. hope this helps :)
Answer:
c) walking in clown shoes is not as easy as it looks!
Explanation:
A process by which a person becomes protected against a disease through vaccination.
Example:include tetanus, diphtheria, mumps, measles, pertussis (whooping cough), meningitis, and polio
Your answer is B., because it is unidentifiable, so if they don't know the source, then why cite it right? :P :D So anyways, that's why your answer is B. =)
I hope I helped! =D