|Question 21Verbal

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Water is constantly moving and changing forms on Earth and in the atmosphere. This process is called the water cycle, and it is typically thought to consist of evaporation, condensation, and precipitation. However, the National Oceanic and Atmospheric Administration seeks ______ understanding of the water cycle to include transpiration, sublimation, and other types of water movement.
Which choice completes the text so that it conforms to the conventions of Standard English?
is expanding
A
has expanded
B
to expand
C
expands
D