120 degC = mass extinction. No one uses Reaumur and Kelvin is only used as a joke or by absolute pedants. Hence, it's Fahrenheit.
I remember being mocked by my professors at school as well when making a mistake. All it did was make me resent them for being assholes to me, it didn't teach me to use units more correctly.
If instead they simply had said "Celcius or Farenheit? You have to be explicit, because ...", I would have learned something and it would have stuck with me.
Professors being nice to students makes the students want to be nice in return, and want to learn as a result.
I still resent every single one of my high school professor that did this sort of shit. All they achieved was getting me to drop out. Joke's on them, I pursued the career they mocked and did better at it than they did at theirs.
And when I see other professors, coaches, teachers and mentors do this kind of shit to students today, I honestly want to slap them silly. This is why I'll continue mentoring whoever I can. Education is the single most important factor in our survival as a species, especially now.