❔Advice needed: positioning towards a full-time M&A offer

Hi all, 

I need some advice for the following situation, would be happy to see your insights and how you would deal with it. 

Background

I am currently an intern, on my way to completing 2 M&A internships at two different places. At both places, I intend to work towards a full-time offer. 

Options

Option A: option I would like to work at, but not my first choice (as for now)

Option B: option I would like to work at, my first choice (as for now)

Expected timeline

Start internship option A -> { I am here }  

End of internship option A: full-time offer

Start internship option B 

End of internship option B: full-time offer

Situation

Now, Ideally I would like to keep the offer at option A open until I am sure that I have worked there and do not feel a fit with the team/company or do not receive a full-time offer at all. 

I am scared that I could burn my bridge with option A, only to end up with no offer for option B, putting me in a very bad spot with no M&A job (as there are a very limited amount of open positions). I could play it safe and accept the offer for option A immediately, but then I will also regret not trying out option B, which in my opinion is a bit better career wise (nicer deals, clients, ...).

I am not sure how to deal with this: can it be done? Can I discuss this with the hiring manager (be honest about it)? How would you try to position yourself to be in the best spot possible? What arguments do you think are valid and which one would immediately smell like bullshit? Please don't hesitate to provide your insights, it would be very useful to me. 

Thanks in advance,