What will this do, and why?

C - Alert Undefined

Here's another way of writing it:

variable declarations are 'hoisted' to the top of the function

(notice: function scoping, not block scoping)

C - TypeError: undefined is not a function

Variable declaration is hoisted, so it's there, but it's not a function yet.

A - I am a lizard

var foo = function() {} = function expression, only foo is hoisted

function foo() {} = function declaration, hoisted whole function

You can call functions declared with a function declaration from anywhere in the scope, but function expressions can only be called after they are assigned.