What does it mean when when we that say that the air get's thinner​

Ms.ringer asked her class "what are the favorite colors of the students in our school" which student correctly deceives ms.ringer's question

2/6 of be by to 2/6 is to 24/72 ?

Which statement explains what upwelling causes? a. upwelling causes tides to rise and fall. b. upwelling causes changes in the direction of currents. c. upwelling causes nutrients, minerals, and tiny organisms to rise. d. upwelling causes currents in the pacific ocean to change direction. i think the answer is c.