Final answer:
The nursing diagnosis that includes 'physical immobility' as a related factor is 'Impaired skin integrity', due to the increased risk of pressure sores and infections from prolonged unrelieved pressure on the skin.
Step-by-step explanation:
The nursing diagnosis that includes the related factor physical immobility is a) Impaired skin integrity. Physical immobility can result in prolonged pressure on the skin, especially in areas where bony prominences are close to the skin surface. This pressure can impede blood flow and lead to breakdown of the skin, resulting in pressure sores or bedsores. These ulcers are not only painful but they also increase the risk of infection since they provide a portal of entry for pathogens.
Physical immobility is also associated with other health complications in the elderly, such as the formation of blood clots and respiratory issues due to poor air exchange. These issues underline the importance of managing physical immobility to prevent further health deterioration.