A Trick Question

poison ivy leaves in 3 sizes and colors

The question is: which of these three leaves IS poison ivy?

They are totally different colors, sizes, shapes, and textures.

Not a hard one, of course: they are all three poison ivy, just at different growth stages.

But it is interesting to see how rapidly the leaves mature and change on a single stalk. Each of these three "leaves of three" came off the main stem right in order, the big green one first, the light yellow-green second, the tiny red last. All within days of each other, yet they look so different. 

In a few more weeks they will likely all three look the same, about like the big green one on the right.

Note that this particular plant has NO notches on the leaves at all, which is not a common, but hardly rare.