For this pause-problem, consider the following study: a researcher would like to conduct an experiment to test the effectiveness of a program designed to raise sat scores. he wishes to obtain a sample of low-scoring high school students, administer the program, and then administer the sat again. he hypothesizes that sat scores will be higher after the program than before. pick out three potential validity threats to this study (internal or external) and describe what the researcher can do to limit each of those three threats

"choosing is refusing" means individuals face an opportunity cost with each decision they make. economists state that every decision involves trade-offs. opportunity cost is the least desirable alternative given up as a result of a decision.

a.indigo and cochineal

b.animal hides

c.silver and gold

e.cacao beans and sugarcane

well its not not rising unemployment and falling inflation.

hope this good !

the factors that the economies of the muslim empires prosper were:

1- land trade routes-located between three continents  

2- sea trade routes

trade contributed to the spread of muslim empires, and with that islamic culture led to a growing feeling of internationalism resulted in the transfer of technology, science, and other cultural forms.