How were the Romans able to move from wooden houses to more permanent structures?

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.

since most of current immigration into the u.s., both legal and illegal, is coming from latin america. it would be very difficult to imagine or rationalize a country my fellow citizens are trying desperately to flee into, would pose a threat to my prosperity or freedom. since the u.s. has a long history of intervention, but no record of permanent occupation, i would not feel oppression is the main objective.  

the largest free trade nation, along with the largest gdp in the world wanting to expand it's economic policy on us, and including us, could only be positive. the u.s. government has no interest in, or way of simply forcing american culture on us. and has no track record of it. other nations that adopted american social culture, or "americanization" did so voluntarily, mainly through the choice of allowing american businesses and u.s. citizens to come into their nations, as free operatives.

that is probably something for you to answer