答案：B

解析：

Choice B is correct. The center of the wall is a distance of 1/2(24)=12 feet from the left end of the wall. If x is the distance from a painting edge to its corresponding end of the wall, then |x-12| is the distance from the painting edge to the center of the wall.

If the painting is centered, then 2|x-12| represents the width of the painting.

Since the painting is 10ft wide, we have 2|x-12|=10.