Answer:
Both studies were controlled experiments.
Step-by-step explanation:
Since in the question it is mentioned that there is a study on the impact of coconut oil on the hair growth.
There is 140 subjects who used the coconut oil for the long time and the other 140 people does not use the ooil
Also 80 subjects would be randomly selected for coconut oil and 80 would be selected to use for placebo
So this two studies represents the controlled experiments and the same is to be considered
Answer:
The first was a observational, the second was a controlled experiment