The requirement "For each customer..." implies that a set of activities should be performed for every item in a collection (the list of customers). The standard BPMN notation for this is the Multi-Instance marker on an Activity or Sub-Process. Option C correctly shows a Sub-Process containing the required sequence of activities ("Request Information", "Receive Information", "Update Database") marked with the Multi-Instance symbol (three vertical bars). This indicates that the entire Sub-Process will be instantiated and executed for each customer.

A. This is too abstract. While the loop marker on a single task implies repetition, it doesn't show the required internal sequence of three distinct activities.

B. The standard loop marker indicates repetition based on a condition (e.g., a while loop). The Multi-Instance marker is more specific and appropriate for iterating over a collection.

D. This diagram incorrectly places the loop marker only on the "Update Database" task, implying that only this final step is repeated, not the entire sequence.

1. Object Management Group. (2013). Business Process Model and Notation (BPMN) Version 2.0.2. OMG Document Number formal/2013-12-09.

Section 10.2.6, "Multi-Instance Activity" (p. 179): "A Multi-Instance Activity is an Activity that is executed multiple times... The instances can be executed in parallel or sequentially." This is the formal definition for "for each" semantics.

Figure 10.37 (p. 180) and Figure 10.38 (p. 181) illustrate the markers for parallel and sequential multi-instance activities.