Programming IQ test: Round 1 & 2

Neil McAllister has compiled two general IQ tests for programmers. Give them a go there are some tricky questions and then some of the humorous variety exhibit A below:

4. What is a singleton?

A) class that is instantiated exactly once, producing just one object of that class

B) complete program that takes up only one line of code

C) data structure, such as a linked list, that contains only one member

D) The typical programmer on a Friday night