How are scarcity, choice, and opportunity cost related?

What will be an ideal response?

Since resources are scarce, we cannot have everything we want. This implies that we must make choices. We can't have everything we want, but we can have some of the things we want, and must choose. But when we choose one thing, we're prevented from choosing one or more other things. The highest-valued alternative good that we don't choose is the opportunity cost of the good we did select.