The user will be presented with multiple options (as radio buttons), and he/she must select one option before proceeding to the next step. The individual sections will be expandable/collapsible for the user to see the content within each panel before making a selection.
The problem I have is whether to place the radio button on the outside (left edge) and expand/collapse arrow on the inside, or vice versa. I'm leaning towards option A because they are interacting with a radio button, and the button is usually on the very left. The arrow icon can be in the inside because the radio button isn't part of the expandable/collapsible content. However, I received a different idea from my supervisor (option B), and I'm wondering which approach is more intuitive.
I've done a search on this and wasn't able to come up with any studies/results. Your feedback is much appreciated!