Question

what happens to seawater density when salinity increases? temperature increases density decreases density increases density remains constant

Explanation:

Seawater density is directly related to salinity. When there is more salt (higher salinity) dissolved in the same volume of water, the mass of the water - salt mixture increases. Since density is mass per unit volume ($\text{density}=\frac{\text{mass}}{\text{volume}}$), an increase in mass while volume remains relatively constant leads to an increase in density.

Answer:

C. Density increases