How does water density change in different marine environments?

Water density varies due to salinity and temperature differences, which is the foundation of option B. In marine environments, both salinity (the concentration of salt in water) and temperature play significant roles in determining the density of seawater.

As temperature decreases, water typically becomes denser, but this is also influenced by the salinity level. Higher salinity increases water's density because salt increases the mass of the water without significantly changing its volume. Conversely, warmer water is generally less dense than colder water.

Understanding this variability is critical for fields such as oceanography, marine biology, and navigation, where different layers of water in the ocean can have different densities leading to phenomena like stratification and thermoclines. Thus, recognizing these factors is essential for understanding how marine organisms interact with their environment and how vessels behave in different water conditions.