How can I show different subsets of my product list, based on a selected option?

To simplify, let's say I have a list of 4 products, and based on the option selected from a single-choice element, I want to show a different subset of the 4 products.  So if the user checks option A, I want to show only products 1, 2 and 3, all preselected.  But if the user checks option B, I what to show only products 2, 3, and 4, all preselected.  Then, the user should be able to uncheck any individual preselected products, and pay the resulting total amount (I'm using the Stripe interface).  Can you suggest the best method for doing this?

I understand that you want to create sub-products for each product on your form. You may use one of the payment tools on the form and configure sub-products to the products. Please check the following guide that can help you with creating sub-products in the payment wizard.

https://www.jotform.com/help/264-Create-Sub-Products-Based-on-a-Product-Option

Hope this information helps! 

No, that's not the issue; sorry if my explanation wasn't clearer.  We have only 4 products: 1, 2, 3, and 4.  No sub-products.  If you choose option A, I want you to see only products 1, 2, and 3, all pre-selected, with the option to de-select any one or more.  If you choose Option B, I want you to see only products 2, 3, and 4, all pre-selected, with the option to de-select any one or more.  Then in either case, calculate the total automatically for payment.

That is not possible to apply to a payment field. You might consider the following workaround:

1) You will need to split your products into native fields such as "Single choice" or "Multiple Choice" fields, and assign a value to each option: https://www.jotform.com/help/301-How-to-Assign-Calculation-Value 

2) You can show the products based on user's answers by applying conditions: https://www.jotform.com/help/316-How-to-Show-or-Hide-Fields-Base-on-User-s-Answer 

3) Then perform the calculations: https://www.jotform.com/help/259-How-to-Perform-Form-Calculation-Using-a-Widget 

And pass the total to the payment field: https://www.jotform.com/help/275-How-to-Pass-a-Calculation-to-a-Payment-Field 

Let us know if you need anything else.

Looks promising, I'll give it a try!  Thanks very much for your help -- Jotform has the best customer support ever!