How can we set conditions on dropdown to how specific options based on a day selected?

If a field shows "monday", the the drop down shows A,B & C. If Tuesday, the drop down shows D,E & F. Etc..

What you are looking for is a widget called Dynamic Dropdowns.

What is great about them is that it allows you to add layers of dropdowns, allowing you to quickly change the data in the dropdown under the other one as if you have set a lot of different conditions, but without actually having a need to do any.

If you would like to add it to your jotform, but are not sure how, please take a look here: How to Add a Widget to your Form

Do let us know how it goes.