Correct answer is (a) amnsard roof
For explanation I would say: The four-sided slopes are not the characteristic feature of only Mansard roofs; the Pyramid roofs also come with this feature. As the name suggests, these roofs are shaped like pyramids, a roof with four sloping sides. These roofs are best-suited for smaller structures, like a farmhouse hut. These roofs are popular in the contemporary architecture, with many structures getting these roofs. The walls of these houses are symmetrical and easy to build. A lower degree pitch works best for such four-sided roofs. They would work even better if the walls were smaller and the roof made for a significant part of the house. It is not only aesthetically pleasing, but also more energy efficient.