f n = 3^2 - 2^2, which of the following is NOT a factor of n?	Choices:	A) 5	B) 10	C) 4	D) 15	E) 20
9-4= 
<gadget id="calculator">9-4</gadget>
<output>5</output>
5 is prime no. any number not multiply with five is not a factor   4
<result>C</result>
f n = 3^2 - 2^2, which of the following is NOT a factor of n?