The 12-factor app methodology, under its eleventh factor "Logs," mandates treating logs as event streams. The application itself should not be concerned with routing or storing its log output. Instead, it writes its event stream to standard output (stdout). The execution environment (e.g., a container runtime, PaaS) is then responsible for capturing this stream, collating it with streams from other processes, and routing it to a centralized destination for analysis and long-term archival. This decouples the application from the logging infrastructure.

B. The application should not manage its own log storage. Writing to a local database violates the principle of treating logs as a simple event stream.
C. The application should not write to log files that are then backed up. The execution environment handles the collection and archival of the log stream.
D. This is incorrect for the same reason as option B; the application should not be responsible for saving logs to any form of local database.

1. Heroku, "The Twelve-Factor App," Factor XI. Logs. The canonical source states, "A twelve-factor app never concerns itself with routing or storage of its output stream...each process’s stream will be captured by the execution environment...and routed to one or more final destinations for viewing and long-term archival." This directly supports the concept of the environment capturing and routing logs to a central location. (Source: https://12factor.net/logs)

2. Cisco, "Cloud Native Technologies and Microservices," Cisco Live Presentation BRKCLD-1001 (2019). This presentation discusses the 12-factor app as a foundational set of principles for building cloud-native applications. In the section covering Factor XI (Logs), it emphasizes that applications should log to stdout/stderr and let the platform (execution environment) handle aggregation and forwarding to systems like ELK or Splunk. (Specific slide reference: "12 Factor Apps - XI. Logs").

3. Pahl, C., & Jamshidi, P. (2016). "Microservices: A Systematic Guideline." In 2016 IEEE International Conference on Services Computing (SCC), pp. 438-445. This academic paper reviews microservices principles, referencing the 12-factor app. It notes under the logging pattern that "microservices should not be concerned about the log storage, but should write logs to the standard output. The environment should be responsible for collecting and processing the logs." (Section IV.A. Guideline G1: The Twelve-Factor App). DOI: 10.1109/SCC.2016.65