The organ which returns water to the bloodstream is the large intestine, represented by option C in the given choices.
The large intestine, also known as the colon, is responsible for absorbing water from the indigestible food residue that passes through the digestive system. After the process of digestion and absorption of nutrients in the small intestine, the remaining waste material enters the large intestine. In the large intestine, water is reabsorbed back into the bloodstream, resulting in the formation of solid feces.
The large intestine plays a crucial role in maintaining the body's water balance by reclaiming water from the waste material. This reabsorption process helps to prevent excessive water loss and ensures that the body retains the necessary amount of water for proper hydration.
Therefore, option C, the large intestine, is the correct choice as the organ responsible for returning water to the bloodstream.