A is the correct choice because the n1-standard-96 machine type directly provides the 96 vCPUs required by the application, ensuring a seamless transition to GCP. B is incorrect as the CPU platform choice (Intel Skylake) does not influence the number of vCPUs available. C is not feasible because modifying a running instance to increase vCPUs to 96 is unsupported and may not yield optimal performance. D is unsuitable because Rightsizing Recommendations do not guarantee the specific vCPU requirement of 96, focusing instead on general performance optimization. For more details, refer to Google Compute Engine machine types.