I believe that the Knight would be the obvious answer.
<em>Requisite</em>
Made necessary by particular circumstances or regulations.
"the application will not be processed until the requisite fee is paid"
synonyms: necessary, required, prerequisite, essential, indispensable, vital, needed, needful
This would mean that the correct answer to your uestion would be C. Nikkita didn't get the job because she didn't posses the [Nesscary/Requisite] (exam?).
Answer:
What is the best thing about Switzerland?
I don't know but the flag is a big plus.
