Final answer:
A bar diagram or bar graph is the best method to display the incidence of specific diagnoses at Healthy Hospital, allowing for an effective comparison among different diagnosis categories.
Therefore the correct answer is option c. bar diagram.
Step-by-step explanation:
The best method to display the incidence of specific diagnoses for the month of January at Healthy Hospital would be through the use of a bar diagram or bar graph. This type of graph effectively compares categories and can show changes over time. A bar graph's bars can represent the number or percentage of individuals with each specific diagnosis.
Vertical or horizontal bars can be used to show the total numbers or percentages of patients within each category of diagnosis, allowing for easy comparison among them. When designing a bar graph, it is important to display the bars in a clear and chronological order, ensure that the graph is legible, and use distinguishable colors for each diagnosis category. Percentages or numbers should be clearly presented on the vertical axis.