Answer:
The answer to your question is letter B
Step-by-step explanation:
a. [: C≡C :] This option is not correct because Carbon only has 4 valence electrons and carbons in this structure have 5, this structure does not exist.
b. [: N≡N :] This option is correct because because Nitrogen has 5 valence electrons and this structure shows that number of electrons.
c. No right choice. This option is incorrect because letter B is correct.