Shayna enlarged a square photo by adding 10 inches to each side so it could be seen on a large poster. The area of the enlarged photo is 256 square inches. In the equation $(x+10)^2=256$, $x$ represents the side measure of the original square photo.



What were the dimensions of the original photo?

A4 inches by 4 inches

B6 inches by 6 inches

C10 inches by 10 inches

D12 inches by 12 inches