ONLY ANSWER THE 3rd question! please i need help

Which of the following areas have the highest population density? a) quebecb) united statesc) californiad) new york city

How does rain water cause erosion and deposition? a. when acidic water soaks into the ground, water dissolves limestone, resulting in the formation of caves.b. when a river overflows it moves downhill resulting in the formation of caves.c. when it rains, water flows into rivers and streams and moves back to land, resulting in the formation of caves.d. when water empties into lakes, sediment is deposited, resulting in formation of caves.

How do hearths affect cultural diffusion? a. a hearth is the destination of cultural diffusion. b. a hearth divides a cultural region in two. c. a hearth is the beginning point of cultural diffusion. d. a hearth is the means of cultural diffusion. e. a hearth is the meeting point of two diffuse cultures.