What are those gap detection methods of A B C in EAC??
How do they works? And which one is the best??

Does this affect the quality and CD structural accuracy??

None of them is best, but they are however very drive dependant and hence, tests needs to be done to find which is best for each drive. If two or all three works fine with a drive, then choose the fastest one. All three methods uses different ways of analyzing the Q subchannel throughout the program area to retrieve the index numbers available for each track(except index 01 which is stored in the toc) and to retrieve their absolute time(MSF).

Then what do A, B, C correspond to?????
This is what I need to know

This thread need attention from EAC builder,
I emailed but no reply come back, googling yields nothing helpful................