Explanation:

option c

• Because of human-driven increased levels of carbon dioxide in the atmosphere, there is more CO2 dissolving into the ocean.
• The ocean's average pH is now around 8.1 , which is basic (or alkaline), but as the ocean continues to absorb more CO2, the pH decreases and the ocean becomes more acidic.
• Ocean acidification reduces the amount of carbonate, a key building block in seawater.
• This makes it more difficult for marine organisms, such as coral and some plankton, to form their shells and skeletons, and existing shells may begin to dissolve.