In one study on the effect of coconut oil on hair growth, 140 subjects who acknowledged being long-time coconut oil users had their hair growth compared with those of 140 people who had never used coconut oil. In a second study, 80 subjects were randomly chosen to use coconut oil and 80 were chosen to use a placebo. Identify the types of studies performed.

The first study was an observational study whereas the second was a controlled experiment.

The first study was a controlled experiment whereas the second was an observational study.

Both studies were controlled experiments.

Both studies were observational studies.

Each study was part controlled experiment and part observational study.