The project manager has constructed a graphical chart categorically representing the frequency of each data occurrence. This is an example of which of the following tools?

A histogram is a graphical representation of the distribution of numerical data. It uses bars of different heights, where each bar represents a range of values and its height indicates the frequency of data points falling within that range, thus showing the frequency of data occurrences categorically.

A Gantt chart is a bar chart used for project scheduling, illustrating the start and finish dates of the terminal elements and summary elements of a project, not data frequency.

An Ishikawa diagram, also known as a fishbone diagram or cause-and-effect diagram, identifies potential causes for a specific problem or effect, not the frequency of data occurrences.

A control chart is a statistical process control tool used to determine if a manufacturing or business process is in a state of statistical control, typically showing data points over time with upper and lower control limits.