В предложении не нужен артикль перед словом MICROECONOMICS
1. Are they preparing for the seminars in microeconomics in the office?
2. Are they preparing for the seminar or for the test?
3. What seminar are they preparing for?
4. They are preparing for the seminar in biology, aren't they?
5. Who is preparing for the seminar in microeconomics?
6. I wonder how they are preparing for the seminar.