The author concludes that the Asian elephant does not run. Why? Because the Asian elephant always has at least two feet on the ground at all times. In addition, it accelerates only by taking quick and longer steps.

We’re trying to prove that the Asian elephant doesn’t run. But do we know from the premises what “running” requires? No. We don’t know what can establish that something doesn’t run. So, at a minimum, the correct answer should tell us what’s required to run.

To go further, we can anticipate some specific relationships that would make the argument valid. Any answer that gets us from one of the premises to “not run” could be correct. For example:

In order to run, something must have fewer than two feet on the ground at some point in time.

In order to run, something must accelerate in a way besides merely taking quicker and longer steps.