what do you say (a poll for the academics)

Here's a question. In casual conversation, when someone you don't know asks you what you do, how do you answer?
1a. I teach.
1b. I teach at [X College/University].
1c. I teach [X Subject]

2a. I work at [X College/University].
2b. I am a professor.
2c. I am a professor at [X College/University].

3a. I am a researcher.
3b. I research [X Topic]/
3c. I do research at [X College/University].

And why do you think you answer the way you do?

For myself, I tend to go with 1a, 1b, or 2a. Which then usually leads into a follow up statement about 1c.

I have more to say about this, but I'm curious to see what other people do, first.