Question

internal waves can be formed by differences in water... density temperature salinity none of the choices

Explanation:

Internal waves are formed due to differences in water density. Temperature and salinity can affect water density. For example, warmer water is less dense than colder water (temperature - density relation), and water with higher salinity is denser (salinity - density relation). So, when there are variations in these properties (which ultimately cause density differences), internal waves can form.

Answer:

All of the first three options (density, temperature, salinity) are correct as temperature and salinity differences lead to density differences which form internal waves. But if it's a single - choice question where only one box can be checked (assuming the question's format allows for that interpretation, perhaps a mis - designed question), density is the most direct answer. However, based on the scientific principle that temperature and salinity affect density (which forms internal waves), if multiple choices are allowed:

• density: Correct (direct cause)
• temperature: Correct (affects density)
• salinity: Correct (affects density)
• none of the choices: Incorrect