Between 1990 and 2000, the annual precipitation in Henan, one of the main agricultural provinces in central China, has fluctuated from 250 to 470 inches per year, causing substantial variation in the productivity of local crops and making it difficult to predict whether or not the rapid economic growth of the province could be sustained in the future.

(a) has fluctuated from 250 to 470 inches per year, causing substantial variation in the productivity of local crops and making it difficult to predict whether or not the
(b) fluctuated from 250 to 470 inches per year, causing substantial variation in the productivity of local crops and making it difficult to predict whether or not the
(c) fluctuated from 250 to 470 inches, causing substantial variation in the productivity of local crops and making it difficult to predict whether its
(d) fluctuated from 250 to 470 inches, causing substantial variation in the productivity of local crops and making it difficult to predict whether or not the
(e) fluctuated from 250 to 470 inches, causing substantial variation in the productivity of local crops and making it difficult to predict whether the

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