Final answer:
Contact time of at least 2 minutes is needed for bleach to effectively disinfect, and the presence of organic material can compromise its effectiveness. Bleach solutions are not stable for long periods post dilution, and the ideal dilution ratio depends on the specific disinfection needs.
Step-by-step explanation:
The statement regarding bleach as a disinfectant is that bleach requires a minimum of 2 minutes contact time to reliably kill infectious agents. Bleach does not work best in the presence of organic materials, such as blood; in fact, its effectiveness can be compromised by organic matter. Bleach solutions can lose stability over time, so it is not correct to say that diluted bleach is stable for 1 month. The 1:9 bleach to water dilution is a common recommendation, but the best dilution can vary based on the intended use and the level of disinfection required.
The effectiveness of chemical disinfectants has historically been compared to that of phenol, as indicated by option A. Bleach, which is a solution of sodium hypochlorite, has been used as a disinfectant and bleaching agent since the 18th century and is known for its bactericidal properties. It must, however, be used correctly to avoid compromising its effectiveness or causing harm to the user.