From all the available options, the one that would not increase the health risk for construction workers would be (D) stable, rarely changing job site environments and conditions.
High number of unskilled labors increase the likelihood that an accident might occur, while high turnover creates instability which in turn might increase the same likelihood due to increased workload while human resources seek a replacement. Multiple contractors and subcontractors mean confusions might arise and accident may likely happen if the risk is not properly managed.
