Task: Class Definition Understanding (ontology: Earth_Environment/SWEET)

Which of the following definitions best describes 'ice sheet'?

A. An the concept is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square km (19,305 square mile).
B. the concept is a gas consisting primarily of methane. It is found associated with fossil fuels, in coal beds, as methane clathrates, and is created by methanogenic organisms in marshes, bogs, and landfills. It is an important fuel source, a major feedstock for fertilizers, and a potent greenhouse gas. [Wikipedia]
C. Sea ice develops from young ice; thickness from 0.3 to 2 meters (1 to 6.6 feet). Sea ice be subdivided into thin first-year ice (white ice), medium first-year ice, and thick first-year ice. First-year ice is distinguished from older ice primarily by having a higher salinity. Undeformed first-year ice differs from older ice in that it is smoother and lacks refrozen melt ponds. Characteristically level where undisturbed by pressure, but where ridges occur, they distinguished by being larger, more angular, and more porous than multiyear ridges.
D. the concept is the scientific discipline that deals with the measurement and representation of a planet, including its gravity field, in a three-dimensional time varying space. Besides the gravity field, geodesists study also geodynamical phenomena such as crustal motion, tides, and polar motion. For this they design global and national Control networks, using Space and terrestrial techniques while relying on datums and coordinate systems

Answer: An the concept is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square km (19,305 square mile).