The correct answer is Both (A) and (R) are true and (R) is the correct explanation of (A). Explanation & Key Takeaways: • Ocean Salinity: • Salinity is the term used to define the total content of dissolved salts in seawater. • It is calculated as the amount of salt (in gm) dissolved in 1,000 gm (1 kg) of seawater. • The salinity of water in the surface layer of oceans depend mainly on evaporation and precipitation. The equatorial region is characterized by heavy rainfall, cloudiness, and humidity. The Evaporation rate and Precipitation both are high in the equatorial region. Hence, the salinity of the ocean in the equatorial region is low. • Surface salinity is greatly influenced in coastal regions by the freshwater flow from rivers, and in polar regions by the processes of freezing and thawing of ice. • Hence Both (A) and (R) are true and (R) is the correct explanation of (A). Important Notes: The relation between rainfall, evaporation, and salinity: • More evaporation ---->more salt left behind. Thus more salinity. • More rainfall ---->more water for salt to get diluted. Hence less salinity.