Setting up quotas is the most effective way to prevent resource consumption from exceeding specified limits, thereby avoiding billing spikes. Budgets and alerts (Option C) only notify you of spending limits being reached but do not control consumption. A spending limit on the credit card (Option A) does not prevent excessive resource usage, and analytics dashboards (Option B) provide visibility but do not prevent excessive consumption. Enforcing quotas ensures that errors or attacks do not lead to unchecked resource usage.