The answer is A.Primary production in the estuaries has decreased.
Primary production is the synthesis of organic compounds from carbon dioxide from the atmosphere. The most of primary production occurs through the process of photosynthesis in plants. Therefore, if there has been a severe loss of mangrove forests around the world, that means the number of plants from the forests is decreased. With less the plants, there is also decrease in photosynthesis process rates and, consequently, primary production decreases.
