Dr. sullivan is conducting a clinical trial to determine if vitamin xx can improve test performance of students in an introductory college nutrition course. dr. sullivan puts all the students' names in a hat and draws names to determine if they will be placed in the control or the experimental group. the experimental group receives a capsule of vitamin xx and the control group a "sugar pill" that tastes and looks identical to the vitamin xx capsule. neither dr. sullivan nor the participants know who is receiving which treatment. this experiment is best described as

rain should be the answer.

for many centuries there were important factors which the economies of the muslim empires developed increasingly. they applied economic procedures in production, investment, finance, taxation and property. they used to tax certain goods (for example: harvest), they charged interest on money lent, they signed contracts with merchants; they relied on a common currency, and they used checks as well as promissory notes. with the money collected by means of taxation, the government provided the needy with an income. in addition, trading networks covered huge distances, so far regions started to have contact and exchange goods. this trade network covered areas of asia, africa and europe.