A researcher is studying how anxiety tends to be experienced by people of different ages. The researcher interviews anxious adolescents, young adults, individuals in their 30s and 50s, and those over 70. The individuals in each age group represent a

Cohort

Explanation:

A cohort is a group of statistical subjects that share a common characteristic. This common characteristic is most of the time a specific period of time, for this reason, cohorts are very useful when statistical studies that take into account different periods of time.

In this case, the cohorts are defined by their age, even if the categories are quite broad: adolescents, young adults, middle-aged adults (those in their 30s and 50s), and the elderly (those over 70). These groups are all examples of statistical cohorts.

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.

your answer would b. the missisipi river

hope i you : )