The example of positive feedback to indirectly maintain homeostasis is the chemical reactions involved in blood clotting. In blood clotting, the process amplifies itself as more and more chemicals are released to form a clot, which is a good demonstration of positive feedback.
The other options describe negative feedback mechanisms, which are involved in maintaining homeostasis by counteracting changes (e.g., sweating to cool down from elevated body temperature or shivering to warm up from low body temperature). The compliment from a coach is not related to physiological homeostasis.