Riddle #149

Question: I can be used to build castles,
but I crumble in your hands.
I can help a man see,
and am found all around the lands.

What am I?

Question: You are driving and you are hungry and thirsty.On the road you find 2 doors.1 has food and 1 has water(drinkable).:Question:What door do you open first????

Question: My thickness is no more than a few centimeters, yet my depth can span to infinity. Although mundane, I intimidate most animals. When in my presence, you will inevitably follow me. What am I?

Question: What tastes better than it smells?

Question: What goes in the water black and comes out red?

Question: What loses its head in the morning and gets it back at night?