Which of the following represents the duration of activities against a calendar?

A Gantt chart is a specific type of bar chart used in project and program management to illustrate a schedule. It visually represents activities or tasks listed on the vertical axis against a time scale (a calendar) on the horizontal axis. The length and position of each horizontal bar correspond to the start date, end date, and duration of an activity, making it the precise tool for representing the duration of activities against a calendar.

A. A pie chart illustrates numerical proportions of a whole; it does not represent data over a time-based calendar.
B. A scatter chart is used to display the relationship between two numerical variables, not for scheduling activities over time.
D. A Pareto chart is a quality management tool that combines a bar and line graph to identify the most significant factors in a dataset (the 80/20 rule).

1. Project Management Institute. (2017). A Guide to the Project Management Body of Knowledge (PMBOK® Guide) (6th ed.). Section 6.5.3.1 Data Representation, p. 210. "Bar charts, also known as Gantt charts, represent schedule information where activities are listed on the vertical axis, dates are shown on the horizontal axis, and activity durations are shown as horizontal bars placed according to start and finish dates."

2. Project Management Institute. (2017). The Standard for Program Management (4th ed.). Section 5.3.3.2 Scheduling Tools, p. 69. This section notes that program schedules are commonly displayed as Gantt charts, which "provide a graphical representation of the schedule information."

3. Kerzner, H. (2017). Project Management: A Systems Approach to Planning, Scheduling, and Controlling (12th ed.). John Wiley & Sons. Chapter 12, Section 12.9, p. 428. The text defines Gantt charts as "bar charts... The length of the bar is proportional to the duration of the activity."