In a Study of Brazil's Frog Population, It Was Reported

Multiple Choice

In a study of Brazil's frog population, it was reported that 90% of frogs had spotted backs. In a subsequent study, only 40% of the total population had spotted backs.
Each of the following explanations would contribute to an explanation for the above statistics EXCEPT:

A) The first study was conducted in April, when young frogs hatch, and young frogs have more spots than older frogs.
B) The two studies used different criteria for determining whether a frog was spotted or not.
C) The studies were conducted in different geographical areas of Brazil.
D) The studies were both conducted at the same time of year by the same research team.
E) Between the two studies, certain species of spotted frogs were decimated by deforestation.