A GIS specialist has a feature class of flights that contains information such as origin...

ArcGIS Pro’sMatrix Heat Chartis designed for visualizing relationships between two categorical fields—such as origin and destination cities—and summarizing a numeric field, like delay time, using aggregate functions (e.g., mean). This type of chart aligns perfectly with the requirement:

It allows you to setColumnto the destination city andRowto the origin city.

Then choose theNumberfield as delay time and theAggregationmethod as "Mean" to calculate average delay.

The chart displays each origin‑destination pair as a cell, color‑coded by the calculated average delay.

Official documentation highlights this example explicitly:

“Create a matrix heat chart to identify the flights that have the highest average arrival delay time between origin and destination city by setting the following properties… Aggregation—Mean; Number—DelayTime”

Other chart types don’t fit the requirement:

Box plotis used to display distributions and identify outliers; it doesn’t aggregate by category pairs.

Scatter plotshows relationships between numeric variables on a continuous axis—not suitable for categorical city‑pair aggregation.

Therefore, the most appropriate choice for summarizing average journey delay by city pairs is theMatrix Heat Chart (C).