The correct answer is B because setting up budget alerts enables you to monitor your spending against predefined thresholds, triggering automatic notifications when these thresholds are approached or exceeded. This feature is designed to aid in project planning and cost management by providing timely alerts to billing administrators and users.

• Option A is incorrect because, while it allows for expenditure tracking, it does not provide automatic alerts for budget thresholds.
• Option C is incorrect as linking a credit card does not offer alerts; charges would continue based on usage without any notifications.
• Option D is incorrect because App Engine does not include settings for budget management.