Don’t mind the writing i didn’t know what the answer is

Which description provides the best objective summary of the article in the passage?

What are the two causes of density in deep current waters? a. salinity (how much salt) of the water and high temperaturesb. salinity (how much salt) of the water and low temperatures c. oxygen content of the water and high temperatures. d. oxygen content of the water and low temperatures

The source of energy shown in the image is (renewable, non renewable, polluting) a drawback of building a dam is that (it will destroy ecosystems, it requires fossil fuels, it won’t be useful for irrigation)