Do you want to achieve your needs within a single flow?
Do you want to give options to decide whether or not the respondee has a related attachment within an outlook email?
Within Office 365 Outlook connector, we could use "Send email with options" action to give options to decide whether or not the respondee has a related attachment, but the respondee could not respond back with one option and their attachments. In other words, the respondee could only respond back with one option.
I afraid that there is no way to achieve your needs in Microsoft Flow currently, if you would like this feature to be added in Microsoft Flow, please submit an idea to Flow Ideas Forum:
I do want to do this within a single flow if possible. I did try using the "Send email with options," but you're correct - I ran to the same issue with not being able to send an option with an attachment.
I am hoping they put in this feature. When you start with the condition "When an email is sent to you..." and if it has attachments, you can manipulate that attachment, but if you don't start with that condition then it is not possible.