One group of scientists believe that sea levels have risen because of global warming. Another group of scientists believe that sea levels have risen because of the melting of polar ice caps. Based on the conclusions of the two groups of scientists, it can be concluded that
A. There is only one true cause of the rise in sea level
B. There are several new ideas about the causes of rise in sea level
C. Only global warming and melting of polar ice can cause rise in sea level
D. All scientists give conflicting explanations about the causes of rise in sea level