If the deepest hole ever dug was about twelve thousand meters deep how do scientists know what is in the inside of the earth

Does anyone know the answers for these

[fw.02]sinkholes are often formed as a result of the actions of. a. heat on recharge b. pressure on aquifers c. acid in groundwater d. minerals in hot springs

Which part of a mountain receives the majority of moisture due to the rain shadow effect? a. the leeward side b. the windward side c. the bottom of the mountain d. all parts of the mountain receive equal amounts of moisture.