Insurers and doctors are well aware that the incidence of lower-back injuries among office workers who spend long hours sitting is higher than that among people who regularly do physical work of type known to place heavy stress on lower back. This shows that office equipment and furniture are not properly designed to promote workers' health
Sitting long hours=> more incidences
physical work=>less incidence although more lower back stress.
Hence chairs are bad in design
We need to tell that the trend comparison is not because of bad designs. Prove that the injuries are not increase in office worker, rather decrease in those who do physical work.
(A) When they are at home, labours ans office workers tend to spend similar amounts of time sitting.
This has nothing to do with incidents at work.
(B) Insurance companies tend to dislike selling policies to companies whose workers often claim to have back pain.
Out of scope
(C) People who regularly do physical work of a type known to place heavy stress on the lower back are encouraged to use techniques that reduce degree of stress involved.
This says that the stress is reduced but how this will translate into the design being bad or not bad? however lets keep it.
(D) Most of lower back injuries that office workers suffer occur while they are on the job.
The injuries can happen because of multiple reasons.
(E) Consistent physical exercise is one of the most effective ways to prevent or recover from lower back injuries.
This help with our intended weakening. In fact better then C also.
Correct me if I am wrong.