You deployed a Deployment with 3 replicas, but only 1 pod is running. What should you investigate?

Correct answer: All of the above

Option B is correct because when a Deployment with 3 replicas has only 1 running pod, the cause could be any combination of issues including node affinity rules preventing scheduling, pod disruption budgets limiting availability, insufficient node resources for the resource requests defined in the pod spec, or nodes being unavailable; investigating all of these is the correct comprehensive approach. Option A is incorrect because while node affinity and pod disruption budgets are valid areas to check, focusing only on them may miss resource exhaustion or node-level failures as root causes. Option C is incorrect because verifying resource requests and node availability is important but still only a subset of the possible causes. Option D is incorrect because while resource requests exceeding node capacity is one possible explanation, it is a single hypothesis and may not be the actual cause; a complete investigation must consider all contributing factors.