"(1) Since the Industrial Revolution, people have been working to protect the environment from the negative effects of manufacturing. (2) Industrial processes use massive amounts of energy and create harmful waste in the process, making them an ecological nightmare. (3) Some proposed solutions to this excessive waste do exist, but manufacturing systems need to be entirely rethought to best align with both human and environmental interests. (4) Closed-loop manufacturing is the only solution." The writer wants to change the underlined portion of sentence 4 (reproduced below) to qualify the passage’s primary claim and express it in less absolute terms.
Closed-loop manufacturing is the only solution.
Which of the following choices best accomplishes this goal?

A. poses the only potential answer
B. provides the most obvious solution
C. enables the single feasible solution
D. represents one effective solution
E. continues to be the best answer