Sea Level Is Expected Rise Due to Continued Melting of the Antarctic

Sea level is expected rise due to continued melting of the Antarctic and Greenland ice sheets. Which of the following best describes why climatologists are likely to have underestimated the rate of sea level rise?

A) ice sheets are melting from within as water flows down through fractures.
B) the volume of ocean water is larger than expected.
C) the volume of ice is larger than expected.
D) the greenhouse effect is more intense than expected.
E) the rate at which ice sheets flow into the ocean is much slower than expected.