4 year old: Mom, where does milk come from?

Me: Cows.

4yo: *suspicious face* Why?

Me: When a mommy cow has a baby cow, she needs to feed her baby so she makes milk. We can take that milk and drink it too.

4yo: *really suspicious face* Where does orange juice come from??

Me: Oranges.

4yo: Where does coffee come from?

Me: A plant.

4yo: Where does ketchup come from?

Me: Tomatoes.

4yo: Oh. Mommy?

Me: Yes?

4yo: Where doe the sea come from?

Me: Water from the sky and water from deep below the earth.

4yo: Everything is so cool.