What do you call a fish without an eye?

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?

Which alphabet letter is a question?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

I am white when I am dirty, and black when I am clean. What am I?

It is a nine-letter word.
The exact opposite of the phrase "friendly and outgoing"
It contains the word "over".
It starts will a vowel.

What is it?

What is so fragile that saying its name breaks it?

How many triangles can you count in the figure given?

How could a baby fall out of a twenty-story building onto the ground and live?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211