Where does the developer need to configure the additional attributes so they are automatically captured in the broad log at the time of sending?

The Target Mapping configuration within a delivery is the precise location where a developer links data from the incoming workflow transition (the target data) to the delivery's context. This interface provides an explicit option, typically a checkbox labeled "Keep this data in the broad log" or similar, for each mapped attribute. Selecting this option instructs Adobe Campaign to automatically capture and store the value of that attribute from the target data into the broad log schema (nms:broadLogRcp) for each recipient at the moment the delivery is sent.

A. Delivery Activity: This is too general. Target Mapping is a specific configuration within the Delivery Activity, not the activity itself.
B. Target Data: This refers to the actual data set being used for targeting and personalization, not a configuration interface for logging.
D. Extend Schema: While extending the broad log schema (nms:broadLogRcp) is a necessary prerequisite to create the field for the new attribute, it does not configure the capture of data into that field during a delivery.

1. Adobe Experience League - Campaign Classic v7 Documentation, "Target mapping": "The Target mapping link lets you link the data from a temporary workflow table to the data in the delivery logs. [...] You can store additional data in the logs. To do this, select the Keep this data in the broad log option." (This section explicitly details the function of mapping workflow data to the broad log).

2. Adobe Experience League - Campaign Classic v7 Documentation, "Enriching delivery content": In the section describing how to add personalization fields from a workflow, the documentation states: "In the Target mapping tab of the delivery properties, you can specify where the additional data is stored. By default, it is not stored. If you want to keep it, for example to use it in other messages, select the Keep this data in the broad log option." (This provides a use-case and confirms the configuration location).