RaviChandra wrote:
The airline industry is cutting its lowest discount fares more widely, more substantially, and earlier this year than it normally does at the end of the summer, a time during which travel usually decreases and the industry uses some lower fares for the attraction of passengers.
(A) during which travel usually decreases and the industry uses some lower fares for the attraction of
"During which" isn't preferable to "when" since "when" is used to modify an event or time.
Also "attraction of" is not preferred to "to attract"
(B) during which travel usually decreases and therefore the industry will use some lower fares for the attraction of
Same as A.
(C) in which travel usually decreases and in which the industry therefore uses some lower fares attracting
"in which" is still not preferable to "when" for the same reasons as above. End of the sentence ends in a fragment.
(D) when travel usually decreases and the industry uses some lower fares to attract
Correct. Uses "when" and "to attract".
(E) when travel usually decreases and therefore the industry will use lower fares for the attraction of
Wordy and also does not use "to attract"