Which parts of the horse should be sponged for cleaning?

The correct answer focuses on the sensitive and often delicate areas of a horse's body that require careful cleaning to maintain hygiene and prevent infections. The eyes, nostrils, and anus are particularly important because they are prone to collecting dirt, discharge, and other debris that can lead to health issues if left untreated.

Cleaning the eyes helps to remove any discharge that can accumulate, reducing the risk of irritation or infection. Keeping the nostrils clean is vital as it aids in the horse's breathing, and debris in this area can lead to respiratory problems. Cleaning around the anus is essential for preventing fecal matter from creating irritations or infections in that sensitive area.

While the other options may involve sponging certain parts of the horse, they do not emphasize the need for cleanliness in areas that are critical for the horse's health and comfort in the same way. For example, sponging the legs, neck, and back mainly helps with surface dirt or sweat but does not focus on the vulnerable areas that can directly affect the horse's well-being. Thus, the choice of the eyes, nostrils, and anus highlights the necessity of maintaining hygiene in critical regions of the horse's body.