Yolanda is planning to put a pool in her backyard. The scaled model below gives the reduced measures for diameter and depth. Not drawn to scale. The yard space is large enough to have a pool that has a diameter of 27 feet. If Yolanda wants to keep the pool in proportion to the model, what will be the depth of the pool? 
 a. 4.5 feet
 b. 5 feet
 c. 6 feet
 d. 6.75 feet