Joanna and Stephanie are researching the effects of global warming. They notice that several types of organisms, such as the armadillos,gnats and alligator are found much further north than they were found 20yrs ago. They concluded that the change of location of these species is directly related to global warming. What would you tell them about the validity of their conclusions?
A - They made a valid conclusion
B - They should test their hypothesis before coming to that conclusion
C - Global warming could not cause species to move to different locations
D - They should research more species to see if others have moved further north over the last 20yrs