A student is interested in the effects of different walking styles on heart rate. He decides to use 30 volunteers from his school for his experiment. All 30 participants find their at-rest pulse rates. Each participant will walk twice for 10 minutes, once using a fast pace but with no arm movement and again using a fast pace, but with an exaggerated arm movement style. The experimenter throws a coin to determine which style each participant will walk first. All participants get sufficient rest between walks to let their pulse rates return to normal. The student then compares increased pulse rate based on the walk with no arm movement to increased pulse rate based on the walk with exaggerated arm movement for each student. Which of the following statements is true? A) This is an observational study, and not an experiment. Therefore no conclusion can be reached regarding walking style and pulse rate.
B) Observations in this study are independent.
C) Blocking is used in this study to reduce difference in increased pulse rates among individual students.
D) Because subjects were not assigned randomly to a control or an experimental group, the design of the experiment was flawed.
E) This is an example of a completely randomized comparative experiment without blocking.