The rate of evaporation at a given place is always dependent on the humidity of that place because if the air is already filled with water vapor, it will not have any place to hold excess vapor and therefore, evaporation will occur at an extremely slow rate. so a is the right answer

**Introduction:**
Evaporation is the process by which a liquid changes into its gaseous state. It occurs when the molecules of a liquid gain enough energy to overcome the intermolecular forces holding them together. Several factors affect the rate of evaporation, including humidity, temperature, wind speed, and surface area. Among these factors, humidity has the greatest impact on the rate of evaporation.

**Explanation:**

1. **Humidity:**
- Humidity refers to the amount of moisture present in the air. It is measured as a percentage of the maximum amount of moisture the air can hold at a particular temperature.
- When the air is already saturated with moisture, it becomes more difficult for the liquid to evaporate. This is because there is less room for additional water molecules in the air.
- As the humidity increases, the rate of evaporation decreases. This is because the concentration of water vapor in the air is higher, reducing the concentration gradient between the liquid and the air.
- Therefore, an increase in humidity decreases the rate of evaporation.

2. **Temperature:**
- Temperature affects the rate of evaporation because it determines the average kinetic energy of the molecules in the liquid.
- When the temperature increases, the molecules gain more energy and move faster. This increased kinetic energy allows more molecules to escape from the liquid phase and enter the gaseous phase.
- As a result, an increase in temperature generally increases the rate of evaporation.

3. **Wind Speed:**
- Wind speed refers to the movement of air molecules. When there is a higher wind speed, the air molecules around the liquid are constantly being replaced by fresh air.
- This constant movement of air removes the water vapor molecules that have evaporated from the liquid, creating a concentration gradient that enhances evaporation.
- Therefore, an increase in wind speed generally increases the rate of evaporation.

4. **Surface Area:**
- The surface area of the liquid also affects the rate of evaporation. A larger surface area provides more space for the liquid molecules to escape into the air.
- When the surface area is increased, more liquid molecules are exposed to the air, leading to a higher rate of evaporation.
- Therefore, an increase in surface area generally increases the rate of evaporation.

**Conclusion:**
Among the given options, the correct answer is option 'A' - an increase in humidity. This is because as the humidity increases, the concentration of water vapor in the air also increases, reducing the concentration gradient and decreasing the rate of evaporation.