For positive integers q and r, which of the following can be written as r^2?	Options:
A) q^2-12	B) q^2-11	C) q^2-10	D) q^2-9	E) q^2-14
Plug values: if q=5, then 5^2-9=4   The question asks which of the following CAN be written as r^2. If q=16, then q^2-9 CAN be written as 2^2.   Answer: q^2-9
<result>D</result>
For positive integers q and r, which of the following can be written as r^2?