The correct answer is choice B. Place a donut-shaped cushion in the client's chair.

Choice A rationale:

Using warm water when bathing the client can be beneficial for maintaining skin integrity, as it helps in preventing excessive drying and irritation. However, for a client with limited mobility, the key concern is pressure ulcer prevention, which is not directly addressed by using warm water for bathing.

Choice B rationale:

Placing a donut-shaped cushion in the client's chair is an appropriate action to maintain the client's skin integrity. Donut-shaped cushions help relieve pressure on bony prominences like the coccyx (tailbone), reducing the risk of pressure ulcers. These cushions distribute the weight more evenly and prevent prolonged pressure on vulnerable areas of the skin.

Choice C rationale:

Massaging reddened areas over bony prominences is contraindicated for maintaining skin integrity. Massaging areas with signs of pressure can cause further damage to the already compromised skin and potentially lead to the development of pressure ulcers. This choice is not suitable for preventing skin breakdown.

Choice D rationale:

Maintaining the client in high-Fowler's position can be beneficial for respiratory and cardiac function, but it does not directly address the issue of maintaining skin integrity. High-Fowler's position may increase pressure on the sacrum and heels, making the client more susceptible to pressure ulcers. It's important to address pressure distribution specifically to prevent skin breakdown.