I'm a relatively fresh graduate and I've been applying for a couple of research assistant position lately. This might have been my fault entirely as I did not realize this professor was handling all the vacancy listings in their department, and so I missed that they were offering two different research topics.

In my application email, I did not specify which I was applying for and I only found out they were interviewing for 2 positions during the interview itself. Maybe I should've addressed that in the interview itself but it's much too late for that now. I was offered the position I was not interested in, it involves a plant whereas the one I wanted was based on a protein. I have had previous experience with plants in my internship so I understand why they thought I was suitable for the position.

My question is, is it rude to ask if the other position is still available or if I'm interested in the other one? If so, can anyone recommend a respectful way of asking through email?

They did mention that there were multiple applicants so I'm worried they've already offered it and asking would just offend them.