The stimulus never tells us what is sufficient to imply something is addictive. The criteria set forth by the author tells us what is REQUIRED (”only if”) to be addictive. But meeting the requirement described does not, by itself, establish that a substance is addictive.

The stimulus does not compare the number of substances deemed addictive now to the number that would be deemed addictive under a different definition. We don’t know whether the current definition is more or less restrictive than the one proposed by the author.

Must be true based on the last sentence. In order to be addictive, then for most habitual users, when they stop using the substance, they should experience extreme psych. & phys. difficulty. So even if some habitual users can stop without that difficulty, in order to be addictive, we still need most users to experience that difficulty when stopping use of the substance.

Not supported, because we don’t know whether most habitual users who stop using the substance described in (D) don’t experience extreme psych. + phys. difficulty. (D) says nothing about whether stopping use causes difficulty.

Not supported. The author tells us at least one thing that is required for addictiveness. We have no reason to think the author believes we can’t come up with a precise definition.