The correct option is A Audi
It is given that people of a certain profession had a tendency to prefer the same cars over all these three years.
Chartered accountants buy 20 cars in 2006.
∴ They can only buy either Audi or Hyundai.
If chartered Accoutants buy Hyundai. Then cars left will be 15, 10, 10 for the year 2005, 2006 and 2007 respectively.
Which is not possible.
Hence, CA prefers Audi cars.