Recoil is the concept of "kicking back" or leaping back after being released. It may be dangerous due to the possibility of injury upon having equipment "leap back" rapidly.
The act of recoiling, whether in a human or in a machine, denotes the act of leaping or pulling back after being released or in response to a trigger. Recoil is largely dangerous due to the potential for injury if workers are not paying careful attention to heavy machinery.
B To recoil is to feel revolted or disgusted, and it is dangerous because it creates job dissatisfaction.
C To recoil is to move quickly and efficiently, and it is not dangerous but desired.
D To recoil is to respond in fear, and it is dangerous because engineers and workers need to remain in control. Losing control could result in serious injuries on the job.