Final answer:
The client's hospitalization on Day 3 is primarily due to a recent right knee arthroplasty option (c), a surgery conducted to alleviate pain and disability from the knee joint, which typically requires a hospital stay.
Step-by-step explanation:
The primary reason for the client's hospitalization on Day 3 is c. Right knee arthroplasty. A right knee arthroplasty, also known as a knee replacement surgery, is a medical procedure to replace the weight-bearing surfaces of the knee joint in order to relieve pain and disability, typically due to osteoarthritis. Given that this procedure usually requires a hospital stay for monitoring, pain management, and beginning of physical therapy, the hospitalization on Day 3 is likely attributed to the recent surgery rather than the management of chronic conditions like osteoarthritis, type 2 diabetes mellitus, or hyperlipidemia, as these are typically managed in outpatient settings unless acute complications arise.