[![enter image description here][1]][1] As you can see, in the above picture, I need to input the county name to finish the parameter setup. Can I change the last part from inputting string to choosing an item from a dropdown list? For example, there are five potential counties I will run the model, like A, B, C, D and E. I want to choose one of them from a drop-down list rather than type the input. I think the Data Type should be something else rather than the String, as shown in the below picture. Any suggestions?

[![enter image description here][2]][2]

I am using ArcGIS 10.3.1 Advance License. [1]: https://i.sstatic.net/0gJWL.png [2]: https://i.sstatic.net/5bVdL.png

As you can see, in the above picture, I need to input the county name to finish the parameter setup. Can I change the last part from inputting string to choosing an item from a dropdown list? For example, there are five potential counties I will run the model, like A, B, C, D and E. I want to choose one of them from a drop-down list rather than type the input. I think the Data Type should be something else rather than the String, as shown in the below picture. Any suggestions?

I am using ArcGIS 10.3.1 Advance License.