|Question 2Verbal

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The minor planet 8764 Gallinago was named after the animal genus that includes snipes. But most minor planets are given only an identification number, largely due to there being over 500,000 such bodies known at present. So while the task of finding a unique name for each minor planet was ________ when few had been discovered, so many minor planets have since been discovered that the task has become nearly impossible.
Which choice completes the text with the most logical and precise word or phrase?
insurmountable
A
substantial
B
ambiguous
C
feasible
D