What is the coolest letter in the alphabet?

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 did Navjot Singh Sidhu put the new January calendar in the freezer

A father is locked up in jail. His wife has gone bankrupt. Their male child has to sell his hotel in order to gain some money. Yet their girl child does not care and is quite happy.

How can someone be so rude?

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

who is silent in the parliament?

What has one eye, but can’t see?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

How many words can a pen with half refill write?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?