The quality improvement tool used to identify special-cause variation in a process is a:

Detailed Explanation:

Special-cause variation represents unexpected deviations due to specific circumstances and can be identified using controlcharts.

Option D: Control Chart

Control charts are designed to distinguish between common-cause and special-cause variations, using control limits to flag unusual patterns.

Option C: Run Chart

Run charts show trends but lack control limits to distinguish special-cause variation.

Options A and B:

Pareto charts and flowcharts categorize and map issues or processes, respectively, without indicating special-cause variation.