What is the productivity for a company that produces 4 kg of plastic parts of
acceptable quality by consuming 5 kg of raw material?

Correct option is A

​$$\text{Productivity is calculated as the ratio of output to input. In this case, the output is the mass of plastic parts produced, and the input is the mass of raw material consumed.}$$​$$\text{Productivity} = \frac{\text{Output}}{\text{Input}} = \frac{4 \, \text{kg}}{5 \, \text{kg}} = 0.8$$

$$\text{Therefore, the correct answer is (a) 0.8.}$$​​​