How did farming tribes on the plains maintain their farming land after they had already cleared it? A. by using a slash-and-burn technique
B. by removing trees that blocked sunlight
C. by carrying out intensive weeding
D. by performing the Green Corn Ceremony

Some organisms have a large geographic range. for example, the norway rat lives on every continent except antarctica. a population of norway rats is the number of rats in one particular area. do you think it’s scientifically possible for a population of norway rats in north america to carry different genetic mutations than a population of norway rats in africa? do you think it’s possible that they carry some of the same mutations? what types of information can scientists learn by studying the genomes of these two populations of rats?