The correct answer to this open question is the following.
Although there are no options provided, we can say the following.
Romans were able to move from wooden houses to more permanent structures because they started to experiment with the use of concrete, cement, and better formulas to increase the quality of this material. Romans were also capable of exploring new ideas to create forms such as vaults and arches. Let's have in mind that Romans originally used a different material called "tufa" which was a volcanic rock. A solid material but not an aesthetical one. Years later, Romans cold mix concrete with volcanic sand to create a more resistant material. With the use of marble, Romans were capable of creating marvelous buildings and temples.