Natural selection is often described with the phrase "survival of the fittest." From the examples in this tutorial

and the variations you see in organisms around you, why do you think the phrase uses "fittest" rather than

strongest, brightest, or largest?

Because fittest is not used to mean strongest, brightest, or largest. Fittest means most or best adapted. So organisms who are most or best adapted survive. Hope this helps!

i it is d i hope it

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.