Like longitudinal research, cross-sectional studies can be threatened by

 The correct answer is :  cohort effects

Explanation:  The cohort study is a kind of analytical research and with observation, where a comparison is made of the frequency of occurrence of an event between two groups, one group is exposed to a factor that is not present in the other group. In a cohort study the research can be prospective or retrospective.

the best and most correct answer among the choices provided by the question is the second choice "less supportive to the war of 1812"

the war of 1812 was a military conflict that lasted from june 1812 to february 1815, fought between the united states of america and the united kingdom, its north american colonies, and its native american allies.

i hope my answer has come to your . god bless and have a nice day ahead!

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.