Option B. Legend or key element is necessary in order to identify the different bars.
How is it so?
A legend or key is necessary to identify different colored bars in a graph. The legend typically provides a key to the colors used in the graph, associating each color with a specific data category or group. This allows viewers to understand the meaning of each colored bar and interpret the information presented in the graph accurately.
Without a legend or key, it may be challenging for viewers to distinguish between different data categories represented by the colored bars, leading to confusion and misinterpretation of the graph. The legend serves as a guide that enhances the clarity and understanding of the graphical representation of data.