I need help trying to figure out what the main idea of the passage is because I don't really understand it.

Question

The natural process of eutrophication is accelerated when inorganic plant nutrients, such as phosphorus and nitrogen, enter the watr from sewage and fertilizer runoff. Eutrophication caused by humans is called artificial eutrophication. Fertilizer from farms, lawns, and gardens is the largest source of nutrients that cause artificial eutrophication. Phosphates in some laundry and dishwashing detergents are another major cause of eutrophication. Phosphorus is a plant nutrient that can cause the excessive growth of algae. In bodies of water polluted by phosphorus, algae can form large floating mats, called algal blooms. As the algae die and decompose, most of the dissolved oxygen is used and fish ans other organisms suffocate in the oxygen depleted water.

a.Decomposing algal blooms deplete oxygen from bodies of water
b.Fertilizer runoff causes artifical eutrophication
c.Artifical eutrophication damages bodies of water
d.Phosphates in detergents are the major cause of eutrophication

I picked d. Is that correct?

They are all correct.