How do some cells become brain cells and others become skin cells, when the dna in all the cells is exactly the same?

Solar energy causes water to evaporate into the atmosphere. how does that water vapor become a cloud? a) as the water vapor goes higher in the sky, the air gets cooler. the cooler air causes the water vapor to condense. b) as the water vapor goes higher in the sky, solar energy causes it to condense around particles of dust. c) as the water vapor goes higher in the sky, the air gets warmer and the water vapor begins to condense. d) as the water vapor goes high into the atmosphere it turns to ice and that's what forms clouds.