I was asked that during my commercial checkride. I didn't know the answer so the DE told me but my mind was in such a fog by the end of the test that I don't remember the answer.
He pointed at the houston class b and asked me what the geographical center was - I told him it was the largest airport in the area. Then he wanted to know which part of the airport was the center - was it the approach end of the runway, the geographical center of the airport, or what?
Then he pointed to the veil around class b and noted that it was offset and asked what the center of the veil was - I didn't know so he told me. But now I'm trying to write up my notes and I can't remember the answer.
Anyway, that's the point of the question...I'm just trying to organize things in case I get asked the same questions again on another checkride.