Which unit of measurement indicates the volume of flow?

The unit of measurement that indicates the volume of flow is barrels per hour. This measurement specifically quantifies how many barrels of fluid are passing a designated point in one hour, making it a direct indication of flow volume over time. In contexts such as oil transportation or processing, barrels are often used as a standard unit for measuring large quantities of liquid, which enhances clarity in reporting and operational efficiency.

While the other choices can relate to flow, they do not measure flow volume in the same way. Meters per hour and feet per minute, for example, express the distance a fluid moves over time rather than the actual amount of fluid being transported. Inches per second also measures speed, not volume. Thus, barrels per hour provides a clear and specific measurement related to the volume of fluid flow, making it the appropriate choice in this context.