Answer the following questions by choosing the most appropriate option.

Transform the given compound sentence into complex sentence.
Cancer is curable and everybody knows this.

A. Cancer is curable is known to all.

B. Cancer is curable is a known fact.

C. Everybody knows that cancer is curable.

D. Everybody knows that cancer can be cured.

Please do not use chat terms. Example: avoid using "grt" instead of "great".