A. Business is feasible and may be accepted if the BC ratio is greater than 1.
B. Business is unfeasible and may be rejected if the BC ratio is less than 1.
Can I use non-feasible instead of unfeasible?
You can use the word not to negate the adjective:
It is not feasible.
Or
It is impossible under the circumstances.
That is the "natural" way to say it. You might find some jargon-riddled contexts where non-feasible is used.