500
1. Sand is made when rocks break into smaller pieces. 2. Over a long period of time, wind, frost, and rain work against mountain cliffs and break off pieces of rock which fall down the mountainside. 3. As the rock bounces down, it breaks off other pieces of rock it hits, and also breaks into smaller pieces itself. 4. The water of rivers and oceans rush against rocks, breaking them into smaller and smaller pieces. 5. The sand particles are cold on my feet. 6. All over the world, the ocean waves tear at the rocks along the shore, wearing them down until finally the rocks are so small they become what we call sand. Which sentence is irrelevant?
What is 5. The sand particles are cold on my feet?