What was the Mita system? A.
a practice of paying taxes through labor

B.
a method of record keeping

C.
a network of royal messengers

D.
a rigid social hierarchy

As of 2013, the world’s total population was about

Pj conducts an experimental study on the effects of soft music during high stakes science testing. he randomly assigns students at the school. in one condition he does not provide music for testing while in the other group he does provide the music. he administers a pretest at the beginning of the year and a posttest at the end of the year. pj’s design is best described as a: a.static group comparisonb. pretest-posttest control group designc.control-group-time-series designd. nonrandomized control-group pretest-posttest design

Which of the following is used as evidence to show changes in living organisms throughout geologic time? a: fossils b: lava c: sediments d: volcano