Carrots, pumpkin, and egg yolks are all good choices for cats. You can refer to the following for specific recommendations.

1. Carrots
Carrots are arguably one of the best foods for cats. They contain a lot of dietary fiber, which is highly absorbent. When this fiber expands in the intestines, it becomes a "bulking agent," effectively increasing satiety and promoting intestinal motility.
2. Pumpkin
Pumpkin is also a great source of fiber! It's rich in pectin, a high-quality soluble dietary fiber that can effectively promote intestinal motility in cats, thus relieving constipation.
3. Egg yolk
It is rich in high-quality protein, which can effectively maintain the normal function of a cat's immune system. This helps cats regulate their metabolic balance and promotes the absorption and utilization of nutrients.