The author believes that full cooperation of world leaders is unlikely, therefore it is overly optimistic to expect stable inflation rates. We want a similar chain of sufficient and necessary. The author will cast doubt on the necessary condition, concluding that the sufficient condition probably won't occur.
Answer choice C starts out looking like a good option. AOD - -> TEO - -> DP However, notice that the conclusion is conditional. "We will be able to arrive at an optimal decision only if we delay the presentation of our proposal." This is perfectly valid reasoning, but it does not match the stimulus. If answer choice C had said, "We will probably not be able to delay our presentation, so don't expect us to arrive at an optimal decision," then it would be the correct answer.