The primary difference between cluster and client execution modes in Apache Spark lies in the location of the driver program. In cluster mode, the driver runs on a worker node within the cluster, managed by the cluster manager (e.g., YARN, Kubernetes). This allows the client to disconnect after submission. In client mode, the driver runs on the client machine (e.g., an edge node), which means the client must remain active for the duration of the job.

• Option A correctly states this distinction.
• Option C is incorrect because client mode still distributes executors across worker nodes; only the driver runs locally.
• Option B, D, and E are incorrect as they conflate execution mode with cloud/local deployments, reverse driver locations, or incorrectly describe cluster configurability. Thus, the only valid answer is A.