To understand why the correct answer is option 'C' (high salinity water), let's first discuss the concept of electrical conductivity and its relationship with salinity.

Electrical Conductivity of Water:
Electrical conductivity is a measure of how well a substance conducts an electric current. In the case of water, it is influenced by the presence and concentration of dissolved ions. These ions can come from various sources, such as salts, minerals, and other dissolved solids.

Salinity:
Salinity is a measure of the total concentration of dissolved salts in water. It is typically expressed in terms of parts per thousand (ppt) or practical salinity units (psu). Salinity affects the electrical conductivity of water because salts dissociate into ions when dissolved in water, making it more conductive.

Classification:
Based on the given range of electrical conductivity (750 to 2250 micro mhos/cm) at 25°C, we can classify the water into different salinity categories:

- Low Salinity Water: This category generally refers to freshwater or water with very low salt content. The electrical conductivity of freshwater is typically below 750 micro mhos/cm. Therefore, option 'A' is incorrect.

- Medium Salinity Water: The electrical conductivity range mentioned (750 to 2250 micro mhos/cm) falls within the medium salinity range. However, this range can also be considered as the transition zone between medium and high salinity. Therefore, option 'B' can be a possible choice, but it is not the most accurate one.

- High Salinity Water: The given range of electrical conductivity (750 to 2250 micro mhos/cm) indicates a relatively high concentration of dissolved salts in water. Therefore, option 'C' is the correct answer.

- Very High Salinity Water: Very high salinity water typically has electrical conductivity values exceeding 2250 micro mhos/cm. Since the given range falls within the high salinity range, option 'D' is incorrect.


Based on the given range of electrical conductivity, water can be classified as high salinity water since the range (750 to 2250 micro mhos/cm) indicates a relatively high concentration of dissolved salts.