Of the following glaucoma agents, which one MUST be refrigerated?

Latanoprost is a prescription eye drop used to treat glaucoma and ocular hypertension. It is important to store latanoprost correctly to ensure that it remains effective and safe to use.
Unopened bottles of latanoprost should be stored in the refrigerator. Once the bottle is opened, it can be stored at room temperature for up to 6 weeks. After 6 weeks, any unused latanoprost should be discarded, even if there is still some liquid in the bottle.