Indicate Whether the Hypothetical Studies Below Represent Correlation or Experimental

Essay

Indicate whether the hypothetical studies below represent correlation or experimental research.
a. A study to determine the effect of exercise on blood pressure.
b. A study shows that students who take more courses in psychology tend to have higher scores on self-esteem.
c. Studies show that as cigarette smoking increases, life expectancy decreases.
d. A study shows that a new spice increased the ability of rats to find their way around a maze.