Fog is a meteorological phenomenon that occurs when air near the ground becomes saturated with water vapor. The saturation of the air can happen when the temperature of the air reaches the dew point temperature, which is the temperature at which the air can no longer hold all of its moisture and some of it condenses into small water droplets that form the fog.
From the options provided, the most likely condition for fog to develop is when a warm, moist wind blows over a cold current. This condition can create a sharp contrast in temperature between the air and the surface over which it flows, causing the warm, moist air to cool rapidly and reach its dew point temperature, leading to the formation of fog.
When a warm, moist wind blows over a warm current, the temperature of the air remains high and there is less chance of the air cooling enough to reach its dew point. Similarly, when a cold, dry wind blows over a warm current, the air is likely to warm up and not reach its dew point temperature. Finally, when a warm, dry wind blows over a cold current, the air is not likely to cool enough to reach its dew point temperature and form fog.
In summary, the most likely condition for fog to develop is when a warm, moist wind blows over a cold current. The sharp contrast in temperature between the air and the surface over which it flows can cause the air to cool rapidly and reach its dew point temperature, leading to the formation of fog.