I took your tables and crafted an insert page for the products. I then added a recordset to this page for the options. After adding in the recordset for the options I added a checkbox to the form on the page. I added a label for the options and set the value to be the optionID. I then added a repeat region around this checkbox and label.
After this I added the MRT server behavior. I choose the lookup table as the relational table. On the next page for the master table foreign key I choose the session variable that is created in the insert and set the type to be numeric. On the next page for the options table I choose the OptionID as the foreign key and for the value selected the checkbox in repeat selection, I set the type to numeric.
When I finish the server behavior and perform a test I insert a new product with some options checked with the checkboxes. When I insert the record there is a new product that is inserted and looking at the lookup table I can see that the product and option values for that product are inserted correctly. I'm including a copy of the working page that I produced.