A nutrition scientist designs a study in which he assigns 100 people to the treatment group and 100 people to the control group. Although the scientist knows each person's group assignment, the subjects are not aware of their group placement. This is an example of .a. double-blind study
b. uncontrolled study
c. single-blind study
d. biased study

The table presents the average day and night temperatures in five cities. it also reveals whether a city receives substantial rainfall (wet climate) or little rainfall (dry climate). which city’s rocks are likeliest to experience frost wedging, and why? a) city a because the consistently subzero temperature would prevent water from melting b) city b because it is a wet region and the temperature fluctuates around the freezing point c) city c because it receives plenty of rain fall and the weather is moderately cool d) city d because the hot and dry weather would cause rocks to absorb water