Although the digestive system is primarily responsible for the breakdown of food, this process can be disrupted if the circulatory system malfunctions. the best explanation for this disruption is that

If the circulatory system malfunctions, all other systems are affected. In living, this system is vital for all organisms. Muscles and organs will not get the necessary nutrients and energy to perform their tasks if even one of the systems are affected. In this case as well, the relation between circulatory and digestive system is crucial. Digestive system can no longer break down food in order to convert them to energy, and tissues and organs can no longer absorb these nutrients to the body, as all cycles in the body are interconnected, the body will deteriorate resulting to cell and tissue death.

The answer is overmatching

D. peatlands,grassland,swamps