What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see? What is it?

There was once a college that offered a class on probability applied to the real world. The class was relatively easy, but there was a catch. There were no homework assignments or tests, but there was a final exam that would have only one question on it. When everyone received the test paper it was a blank sheet of paper with a solitary question on it: 'What is the risk?'.Most students were able to pass, but only one student received 100% for the class! Even stranger was that he only wrote down one word!
What did he write?

Why is it very easy to weigh a fish?

What is harder to catch the faster you run?

What's the only room from which no one can enter or leave

What has no start, end, or centre?

Prove that the below maths equation is true.

8 + 8 = 91

Who always enjoys poor health?

Which country gets ill every time?

What type of tree can I carry in my hand?