Which of the following arrangements consists of single cells?

The correct option reflects the fact that all the listed arrangements can consist of single cells. Staphylococci are typically arranged in clusters, resembling a bunch of grapes, but individual cells can be considered separately. Streptobacilli are usually found in chains; however, they too can exist as single cells. Vibrios, which have a curved shape, can also be found as single organisms. Therefore, it is accurate to say that each of these arrangements can include single cells as part of their characteristics. Recognizing that certain arrangements may typically appear in clusters or chains does not exclude the possibility of single cells existing within those arrangements. This reinforces the understanding that microbial arrangements can exhibit variability depending on growth conditions or stages of division.