Which of the following statements is true regarding the Bulk API and SOAP API?

The Bulk API is designed specifically for handling large volumes of data efficiently, and it can process records in large batches, which includes the capability to work with attachments. When using the Bulk API, attachments can indeed be sent as part of the payload in a single ZIP file. This feature simplifies the management of multiple attachments by allowing them to be grouped together for processing, reflecting the Bulk API's strength in data manipulation for large datasets.

The other statements do not accurately represent the characteristics of the Bulk and SOAP APIs. The Bulk API does have DML limits that apply when it is interacting with Salesforce, contrary to the first statement. The SOAP API does not provide job monitoring features directly from the Salesforce setup menu as described. Lastly, while the SOAP API does relate to handling records, it does not inherently prevent record locking contention for parent objects in Master-Detail relationships, so that point is misleading.

Thus, the capability of the Bulk API to handle multiple attachments through a single ZIP file stands out as the correct statement for understanding how these APIs function.