Can I make it so that each drop down option can only be used once on an input table?

Thank you :)

If I understand you correctly, you want to have a unique selected option for every dropdown in the Input Table? If yes, unfortunately, this isn't possible in the Input Table. What you can do to achieve this is to use basic dropdown field instead and add a conditional logic to compare each selected options. Here's the guide about Smart Forms Using Conditional Logic.

Please let us know if you need further assistance.
Regards.