Students in Mr. Painter's science class studied samples of pond water using a microscope. To prepare for the experiment, the students placed a drop of pond water on each microscope slide, and then covered the drop with a cover slip that was marked with a 1 mm grid. Using the microscope to view the slides, students counted how many of each type of organism they found in each 1 mm square. Finally, each student calculated the total number of each type of organisms. Their data is shown below. Which organism is the least plentiful in the pond water studied? A. amoeba B. volvox C. euglena D. paramecium

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.