En qué/ ¿A qué

Question

Re: ¿En qué trabajas / trabaja? What do you do?
¿A qué te dedicas / se dedica? What do you do?
Hello,  Hope you, the team and families and friends are all well in these difficult times.
I was wondering what the difference is if I were to say:  "¿A qué trabajas?   Since per the lesson this means:
"If you want to ask someone what he/she does for a living, you can ask this way:
¿En qué trabajas?
What do you do? (Lit: In what do you work?)
I included "trabajas" in my reply, but it was marked as incorrect.
Thank you for being there and helping out.
Nicole

Accepted Answer

Hola Nicole
¿Cómo estás? Nice to hear from you.
I'm not sure which is the test question that you got wrong by answering "trabajas" as you don't specify, but to answer your question, if you use the verb "trabajar" then you can only say:
¿En qué trabajas? 
[literal translation "In what do you work?"] or more naturally translated as What do you do? What do you do for a living? 
You cannot use a different preposition, so you cannot say: ¿A qué trabajas? (incorrect)
There is another way to ask the same question, which is slightly more formal but also very commonly used:
¿A qué te dedicas? 
[literally: To what do you dedicate yourself?] and again this would be translated as What do you do (for a living)? What's your job? 
You cannot use a different preposition here, so this would be incorrect: ¿En qué te dedicas?
So, each verbs uses a different preposition. 
I hope this clarified it.
Inma