Final answer:
The correct answer is A. Chlorine bleach: 100 ppm, QAC: 200 ppm (unless Oasis QAC: 400 ppm).
Step-by-step explanation:
The correct answer is A. Chlorine bleach: 100 ppm, QAC: 200 ppm (unless Oasis QAC: 400 ppm).
In the context of bleach strength, ppm stands for parts per million. It is a unit used to express the concentration of a substance in a solution.
For chlorine bleach, the recommended strength is 100 ppm. This means that for every million parts of the solution, 100 parts should be chlorine bleach. Similarly, for QAC (Quaternary Ammonium Compound), the recommended strength is 200 ppm, unless it is Oasis QAC, in which case up to 400 ppm is acceptable.