Final answer:
A Gantt chart is a graphical network model that depicts a project's tasks and the relationships between them. Therefore, the correct option is A.
Step-by-step explanation:
A graphical network model that depicts a project's tasks and the relationships between those tasks is called a Gantt chart. A Gantt chart is a bar chart that displays the start and end dates of each task as well as their duration. It also shows the dependencies between tasks, allowing project managers to visualize the sequence in which tasks need to be completed.