Exchange rate is the correct answer. Exchange rate is the value of one currency for the purpose of conversion to another.
Answer:B&C
Explanation:
Mesopotamia, the area between the Tigris and Euphrates Rivers (now Iraq), is often referred to as the cradle of civilization because it is the first place where complex urban centers grew.
Answer: Observational Study
Explanation: An experiment requires a scientist to observe subjects of the study under specific conditions where an independent variable is involved and controlled by the scientist.
An observational study on the other hand is in an uncontrolled environment and the scientist does not have any control on the variables. An example is polls. The purpose of this type of study is to get statistical values without interfering with the the subjects of the study.
