The temperature differences seen between quito, ecuador, and guayaquil, ecuador, illustrate the effect of ocean currents cloud cover altitude

The answer would be altitude. 
Quito has the altitude of  2.850m, while Guayaquil has the altitude of 5m.
This can lead to the vast difference in climates.
The most noticeable difference is that temperature drop with increased altitude.
For each 1,000 foot rise in altitude, there is a 4°F drop in temperature.

The answer is a.  i hope this