The best way to rewrite the sentence while ensuring correct usage of standard written English is:
A: "Ever since the sting operation, there has been much opposition from those who maintain that it was an unauthorised act."
This option correctly uses "those" instead of "they," which maintains grammatical correctness in the context.
The correct option is (A): Ever since the sting operation, there has been much opposition from those who maintain that it was an unauthorised act.
Among scientists, the discovery of the double helix structure of DNA and the genetic code it incorporates is widely regarded to be one of the most significant scientific discovery of the twentieth century.
If the President knew that his allies would let him down so suddenly, he would have handled them with the greatest care.
Although the new policy aims to increase efficiency, reducing costs, and enhancing employee satisfaction, some employees feel that the changes are too abrupt and poorly communicated.