Final answer:
The body eliminates excess water mainly through the skin by the process of sweating. The skin, as a part of the excretory system, aids in regulating body temperature and water balance.
Step-by-step explanation:
The body eliminates excess water primarily through the excretory system, which includes the kidneys, large intestine, liver, skin, and lungs. The correct answer to the question is D. skin. The skin has sweat glands that release sweat, which is composed of water and electrolytes, to help cool and moisturize the skin surface. While other parts of the excretory system contribute to water balance and waste elimination, the spleen, adrenal glands, and lymphatic system are not primarily responsible for the direct elimination of excess water from the body.