Commentator: The worldwide oil crisis of 1973 was not due to any real shortage of oil, but was the result of collusion between international oil companies and oil-producing countries to artificially restrict the supply of oil in order to profit from higher prices.
Conclusion
The oil crisis of 1973 wasn't due to the shortage of oil but rather the collusion between oil companies and oil-producing countries to restrict supply in order to profit from higher prices.
Evidence (this is shown by the fact that)
After 1973, the profits of oil companies showed large increases, as did the incomes of oil-producing countries.
Evaluate
Given that ... the profits of oil companies and oil-producing countries rose greatly after 1973, How could we argue that ... the oil crisis of 1973 was caused by a real shortage of oil, and wasn't just the result of collusion?
Well, let's start by supposing there was a shortage of oil. As supply shrinks relative to demand, the price of oil would rise. People used to pay $1 / gallon and now they're paying $3 / gallon, as a reflection of demand outpacing supply.
Meanwhile, Profit = Revenue - Expenses
If people are paying higher prices due to short supply, then the revenue per gallon has increased. Have the expenses of the oil producers increased?
There's not necessarily any reason to think expenses went up, unless it's common sense that when oil is in short supply, oil producers have to spend more money to extract/refine/distribute it.
So it's reasonable to think that if gas prices rise due to short supply (while expenses of producing gas stay pretty stable), then that would cause the profit margin on gas to go up all on its own.
Would that explain the profits of oil companies and oil-producing countries going up after 1973? Maybe so, maybe not. Since oil was in short supply, the overall total gas being sold is lower. So even though their profit margin on gas would go up, their overall profits might not go up because of lower volume of sales.
Still, it's coherent to argue that depending on how much revenue and expenses did / didn't go up, a short supply on its own could explain an increase in profits.
But we would probably guess that what LSAT really wants to test is the famous Causal reasoning flaw. The author is presenting a Curious Fact premise:
One possible explanation is that the companies/countries were colluding to artificially jack up the price in order to boost profits. But that's not necessarily the only possible explanation, so it's flawed for the author to be so sure of her causal interpretation of these events.
Goal
Look for an answer calling out the author's failure to consider Alternate Explanations for why the profits rose after 1973, or look for an answer to highlight something that would make the author's causal storyline (oil companies/countries colluded) seem less plausible.