Ok, after answering D incorrectly I struggled alot to figure this out.
Here are my two cents why B and not D ( the rest are easily eliminated)
B. stiff fines are not the only way to collect past due corporate taxes.
Rule 1: find the conclusion: to collect the taxes by forgiving the fines. stiff fines are not the only way to collect taxes, therefore the tax agents
can find an alternative way (which is forgiving the fines) to reach their goal (or the conclusion). This assumption fits the argument but still is not bulletproof.
to make it bulletproof: we know assumption MUST hold true or the argument will break down.
If stiff fines ARE the only way to collect taxes, then the conclusion of "collecting taxes by forgiving fines" will fall apart! because when you there is no way except stiff fines to collect taxes, how can you forgive them to hit the conclusion?
D) past due taxes cannot be collected without a reduction in penalties.
Rule 1: find the conclusion: to collect the taxes by forgiving the fines. past due taxes cannot be collected without a reduction in penalties, therefore tax agents
must reduce fines to reach their goal (or the conclusion). This ALSO fits the argument but still is not bulletproof.
to make it bulletproof: we know assumption MUST hold true or the argument will break down.
If past due taxes CAN be collected without a reduction in penalties, then the conclusion of "collecting taxes by forgiving fines" WONT fall apart, because at this point it comes to the generocity of the tax agency to forgive the fines or not!
By this logic, D is eliminated.
While going through this question I noticed two
boldfaced words that caught my eye, I think they play a key role here, but it is pretty blurry.