IN October 2015, more than 350 landmark in more than 90 countries were lit blue, the official colour of the United Nations. What was the occasion?

A

$$70^{th}$$ Aniversary of United Nations

B

$$90^{th}$$ Aniversary of United Nations

C

$$50^{th}$$ Aniversary of United Nations

D

$$60^{th}$$ Aniversary of United Nations