| In a closed-loop process control system, what is meant by the proportional mode of control? |
| A) It is a control mode that produces a control action that is proportional to the gain. |
| B) It is a control mode that produces a control action that is proportional to the rate at which the error is changing. |
| C) It is a control mode that produces a control action that is proportional to the accumulation of error over time. |
| D) It is a control mode that produces a control action that is proportional to the error. |
