What’s the answer ?

Can someone me do math because i am having a breakdown rn because i don’t get it

The domain of a function can be represented by which one of the following options? o a. a set of output values o b. a set of f(x) values o c. a set of input values o d. a set of both input and output values

Find the length of the normal and the angle it makes with the positive x-axis. (see pictured below)