Final answer:
A bar graph is ideal for displaying the number of hours billed by each partner at a law firm, as it allows for clear comparisons and shows total numbers effectively. A pie chart can also be used if illustrating the proportion of total hours billed by each partner is desired. The correct option is a & c.
Step-by-step explanation:
The optimal way to display the number of hours billed by each partner at a law firm last year would be through a bar graph. The bar graph effectively shows comparisons and can display the total numbers of hours clearly.
Each bar would represent a different partner, and the height of the bar would indicate the number of hours they billed. For enhanced readability, ensure the graphical representation is large enough and the colors used for each bar are distinguishable.
If the data is to present the proportion of hours each partner contributed out of a total, then a pie chart could also be suitable, as it represents the corresponding percentage each partner contributed to the whole. The correct option is a & c.