Jack just read an interesting study regarding middle school children's use of computer-animated simulations to learn introductory chemistry. Although he is a physics professor he wants to see if the benefits of simulations are also found in college physics learners. Jack's research topic is best described as a study that:.
a. tests theory.
b. is a replication.
c. is developed thorough library search.
d. comes from personal experiences.

b. is a replication

Explanation:

Replication is the term given to repeating the same research study in different environment  and with changed subject. It is done to decide whether core finding of first study still holds true for other situation and context or not.

here impact of computer simulation helped chemistry students. Now jack  wants to see if simulation van help student in physics or not thus impact of simulation is being researched again and hence it is replication research methodology.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

credit card number 4 is the right answer