The biodiversity of cultivated crops is currently under threat from industrial farming and climate change. The extinction of important crop could cause mass starvation. How could humans best cooperate using a seed bank to prevent extinction of an important crop?
A. Farmers could plant all the seeds until they run out.
B. Governments could trade seeds in exchange for goods.
C. Scientists could study threatened varieties to find ways to replace them.
D. Grocery stores could sell the seeds as food,

Toward the end of the roman empire, what caused a decrease in the use of coined money tell me now

Which of the following  bestillustrates a negative reinforcer?               a.  copland gives up candy to stave off chronic acid indigestion.    b.  nancy learns that she prefers chocolate over vanilla.    c.  carmine changes his major to english lit after failing a math exam.    d.  on a hot day, lindberg always drinks lemonade.

The authors of the paper "fudging the numbers: distributing chocolate influences student evaluations of an undergraduate course"† carried out a study to see if events unrelated to an undergraduate course could affect student evaluations. students enrolled in statistics courses taught by the same instructor participated in the study. all students attended the same lectures and one of six discussion sections that met once a week. at the end of the course, the researchers chose three of the discussion sections to be the "chocolate group." students in these three sections were offered chocolate prior to having them fill out course evaluations. students in the other three sections were not offered chocolate. the researchers concluded that "overall, students offered chocolate gave more positive evaluations than students not offered chocolate." indicate whether the study is an observational study or an experiment. give a brief explanation for your choice.