Agree - doubt that D is correct.

"In a location-ready design, it is important to ensure that access points are not clustered in the interior and toward the center of floors. Rather, perimeter access points should complement access points that are located within floor interior areas. Access points should also be placed in each of the four corners of the floor, and at any other corners that are encountered along the floor perimeter. These perimeter access points play a vital role in ensuring good location fidelity within the areas they encircle, and may participate in the provisioning of general voice or data coverage."

i highly doubt this is the correct answer , i think it should be int the perimeter of each floor and this is how we reach the deployment of location based, as 3 APs need to track the object for accuracy and all, but putting it in the center of each floor doesn't have any taste and doesn't sound right at all!!!!