The correct answer is C because it directly addresses the requirement to store logs in a specific region (europe-west4) by creating a new log bucket in that region and redirecting the _Default bucket to it. This approach is supported by Google Cloud documentation on regionalized logs and log bucket management, which states that after creating a log bucket, its region cannot be changed, necessitating the creation of a new bucket in the desired region and redirecting sinks. Option D, while applicable for setting default storage regions at the organization level, is less suitable here because the question specifies a new project, and using organization-level settings might affect other projects unnecessarily. Option A (organization policy constraint) does not control log storage regions, and Option B (log sink to Cloud Storage) does not ensure logs are stored in the desired region for Cloud Logging buckets. The community discussion shows a consensus (62% for C) and references to official documentation reinforce C as the optimal choice for project-specific regional compliance.