Which is the lightest?
We’re shown three different objects, a feather, a mouse, a computer mouse, and a dog. And we’re asked to pick the one which is the lightest. So we’re looking for the object which weighs the least. The feather would be the lightest. Maybe you’ve heard the expression as light as a feather.
We compared three objects, a feather, a mouse, and a dog. The object which weighs the least is the feather. The feather is the lightest.