Which of the Following Is Correct Regarding Mean Sea Level

Multiple Choice

Which of the following is correct regarding mean sea level?

A) A consistent value has yet to be determined due to all the variables involved in producing the tides.
B) It is at the same level along the entire North American coast.
C) It is calculated based on average tidal levels recorded hourly at a given site over a period of many years.
D) It has very little variability across all ocean basins and, therefore, is treated as an absolute value.