Which cost system is suitable for a large scale business having small percentage of profit? A) fixed cost (b) Variable cost?

Keeping the option to Fixed and Variable, I would say, the industry does matter. But more importantly, I think Fixed is more valid in large companies then variable.

A good entrepreneur has time-tested instincts, but a great entrepreneur knows analysis and instinct are the keys to smart business decisions.
C.V.P (Cost, Volume, and Profit) Analysis will help to make decision.