Final answer:
The hormone dependent upon chromium for optimal activity is insulin, which plays a crucial role in glucose metabolism and blood glucose regulation.
Step-by-step explanation:
The hormone that is dependent upon chromium for optimal activity is insulin. Insulin is a hormone produced by the pancreas that plays a crucial role in glucose metabolism and maintaining blood glucose levels. Chromium helps insulin to function properly by increasing its binding affinity to cell receptors and enhancing its activity in promoting glucose uptake by cells.