Here's a problem to solve: Both southern California and southern Nevada are arid to semi-arid regions. Which of these has a large influence on the climate in southern California but has little influence on the climate in southern Nevada?

Among the 4 following options, which is the correct answer?

- A: availability of fresh water
 
- B: varieties of plant life
 
- C: changes in elevation
 
- D: proximity to the ocean
 