How to set the answer in one field based on the response in another?

I want to automatically select the Email address based on the Name selected. How can I do this?

You may setup conditions on the form using Update/Calculate field to select the email address in the dropdown. Please refer to the guide below that can help you with this.

https://www.jotform.com/help/268-How-to-Insert-Text-or-Calculation-into-a-Field-Using-Conditional-Logic

Please give it a try and let us know if you need any further assistance. We will be happy to help.