Is the virtual photon a particle?

I just saw an exam question: Write down the antiparticle for the virtual photon.

The answer was "virtual photon".

Is the question even a meaningful one? If so please explain why?

Answer

No, the virtual photon is not a particle, since a virtual particle is what one calls the internal lines in a Feynman diagram, and there are no asymptotic particle states associated to these lines, so a virtual particle is not a particle in the usual (or any other rigorous) sense.

Therefore, the question is non-sensical because it is not clear what an antiparticle of a virtual particle would be, since a virtual particle isn't a particle state to begin with.