"To improve" is correct idiom. SO ABC are out. Took 1.03 mins
(A) at improvingit , the gas-guzzling SUV, continuing its decline in the market, production ceasing
(B) at improvingit , the gas-guzzling SUV continued its decline in the market, to cease production
(C) at improvingit , the gas-guzzling SUV continued declining in the market, and production was ceased
(D) to improveit , the gas-guzzling SUV continued its decline in the market, and production was ceased
(E) to improve it,
...
(A) at improvingit , the gas-guzzling SUV, continuing its decline in the market, production ceasing
(B) at improvingit , the gas-guzzling SUV continued its decline in the market, to cease production
(C) at improvingit , the gas-guzzling SUV continued declining in the market, and production was ceased
(D) to improveit , the gas-guzzling SUV continued its decline in the market, and production was ceased
(E) to improve it,
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