However often bus passengers might complain that there is inefficiency in the current system and that the local transportation bureau has done little to remedy the delays, it has been hard to convince state authorities that help is necessary to bring about a solution.

A) However often bus passengers might complain that
B) Despite the complaints of bus passengers to the fact
C) Although bus passengers complain
D) Even though bus passengers complain
E) There is agreement among bus passengers that
_________________

However often bus passengers might complain that there is inefficiency in the current system and that the local transportation bureau has done little to remedy the delays, it has been hard to convince state authorities that help is necessary to bring about a solution.

The first obvious split is absence/presence of "that" at the end. We need "that" to maintain parallelism: bus passengers might complain that ... and that .... So only A and E work.


E) There is agreement among bus passengers that - absence of "However" leads to two independent clauses connected just with a comma (comma splice):
There is agreement among bus passengers that there is inefficiency in the current system and that the local transportation bureau has done little to remedy the delays, it has been hard to convince state authorities that help is necessary to bring about a solution.

Very similar question: https://gmatclub.com/forum/however-much ... ml#p396061