In interviews, I would like to see you be assertive enough to keep the aircraft from crashing into the ground. Whatever it takes, call it out loudley "Ca,Go around NOW!" Call it out with ATC, and if it requires more, then do your JOB! Why does it have to be a fight for the controls, how do you know the other pilot isn't asleep? Microsleep issues do exist! It may not be intentional, maybe their INT volume got turned down accidentally, or they're in a daydream. I doubt anyone is gonna wrestle with you that low if you take the controls, If the Capt. is crazy enough to fight you for the controls, you have bigger problems, but by adding GA power, will arrest the descent rate and get you climbing, and hopefully this stubborn Capt will be shaken from his/her zone.
There isn't a right or wrong answer, most interviewers are just looking to see what your level of assertion is? Either answer will be acceptable, they also want to see your answer, then see if they can get you to change your answer, by their reaction to your answer.