How does increasing salinity affect the density of seawater, assuming other factors remain constant?

The correct option is It causes density to increase..

Explanation

The density of seawater is a measure of its mass per unit volume. It is primarily influenced by three factors: temperature, salinity, and pressure. Understanding the relationship between dissolved salts (salinity) and density is fundamental to oceanography.

Detailed Analysis:
Salinity refers to the total amount of dissolved solid material in water. When salts are dissolved in water, they add mass to the solution. While the volume of the water may change slightly due to the molecular arrangement, the increase in mass is significantly greater relative to the volume. Therefore, adding dissolved salts increases the mass per unit volume.

• Direct Relationship: There is a positive correlation between salinity and density. As salinity increases, the density of seawater increases.
• Comparison: Freshwater is less dense than saline water because it lacks the additional mass provided by dissolved salts.

Key Takeaway:
Assuming temperature and pressure remain constant, an increase in salinity directly causes an increase in the density of seawater.