SAT math practice question: Factors of an expression

 
Try the following SAT math practice question (No Calculator) that tests your understanding of factorization of algebraic expressions commonly tested on the SAT.

Question(No Calculator):

Which of the following expression is NOT a factor of $x^4 – 13x^2 + 36$ ?

1. $\quad x-2$
2. $\quad x-3$
3. $\quad x+3$
4. $\quad x+4$