Which of the following describes a challenge presented by Canada's population?

Historians are researchers of the past or people who understand the history of people. with this field, they must possess qualities such as being unbiased, patient, efficient reader, has a knack for logic and critical thinking and reasoning, disciplined, open-minded, resourceful, with good analytical ability, good reasoning skills and problem solving!

It is nonrenuable which means that once you have used it, it's gone forever.

Ithink its b but i'm not sure.