What decreases photosynthesis in bodies of water? 

A)  sediment or suspended matter 
B)  heat 
C)  inorganic plant nutrients 
D)  disease-causing organisms

Sediment or suspended matter can block sunlight from reaching the photosynthetic organisms in bodies of water, reducing their ability to carry out photosynthesis. Heat can also have an impact on photosynthesis, but it is not specifically mentioned as decreasing it in bodies of water. Inorganic plant nutrients can actually increase photosynthesis, as they can provide essential nutrients for the photosynthetic organisms. Disease-causing organisms may also have an impact on photosynthesis, but it is not specified how they would specifically decrease it.