Can I hide radio buttons based on answers given elsewhere in the form?

can I hide radio button options in the question 'how will you travel to conference?' based on what location they have selected in the 'your location' drop down?

I can only see the option to hide entire questions 

If what you want to achieve is having conditions to show/hide individual options in a radio button field, I think this is not possible because the radio button is regarded as a single field.

I can see you have found a workaround that do it pretty well. You might simply need several radio button fields.