NEED HELP QUICK PLEASE!!!! what are the four reasons for variations in salinity in various oceans

Salinity, which refers to the saltiness or the amount of salt dissolved in water, varies in the oceans due to several factors. Here are four reasons for the variations in salinity in various oceans:

1. **Evaporation**: When water evaporates from the ocean surface, it leaves the salts behind, which increases the salinity of the remaining water. Therefore, regions with high temperatures and intense sunlight tend to have higher evaporation rates, leading to higher salinity levels. This is particularly noted in the subtropical regions where evaporation is high and precipitation is low.

2. **Precipitation**: Rainfall and other forms of precipitation such as snow and sleet can dilute seawater, leading to lower salinity. Areas along the equator, coastal regions subject to monsoons, and regions influenced by melting ice typically have lower salinity levels because they receive significant precipitation or freshwater input from ice melt.

3. **River Inflow**: Freshwater input from rivers can significantly decrease the salinity of the ocean into which they flow. This is seen at the mouths of large rivers, like the Amazon or the Mississippi, where an influx of freshwater mixes with ocean water.

4. **Ice Formation and Melting**: When sea ice forms, it excludes salt, leading to an increase in salinity in the surrounding water. Conversely, when ice melts, it releases freshwater into the ocean, reducing the salinity of the water. This is particularly relevant in polar regions.