1.) The answer would be D.Earth's rotation, since the rotation makes the air and wind direction appear to be going in a different direction than it really is due to the earth rotating (this deflects the winds)
2.) The answer would be C.Relative Humidity, since this is ratio of water vapor in the air to a given area, while humidity is simply the amount of water vapor in the air in general.
3.) B. Warm Front, since cold fronts usually bring stormy weather, while the weather conditions brought by a warm front are typically more mild.
4.) For this one, I'm not sure, but I'm pretty sure the closest answer would be C.4. The way I have learned this is that there have been 5 major ice ages, however the choice isn't on there.