Proximate cause in this case is this

His contracting pneumonia after falling into a water body from the horseback
Dying of the illness in the hospital
Ramesh falling off a horseback and suffers a grave injury
Falling off the horseback

The correct answer is D. Falling off the horseback.

The proximate cause is the act or event that is closest in time and space to the injury or death. In this case, Ramesh fell off the horseback, which caused him to suffer a grave injury. This injury led to him contracting pneumonia and dying in the hospital. However, the proximate cause of his death was the fall from the horseback, not the pneumonia.

Option A is incorrect because contracting pneumonia is not the proximate cause of Ramesh’s death. Pneumonia is a secondary condition that developed as a result of the grave injury that Ramesh suffered when he fell off the horseback.

Option B is incorrect because dying in the hospital is not the proximate cause of Ramesh’s death. Dying in the hospital is the result of the pneumonia, which is a secondary condition that developed as a result of the grave injury that Ramesh suffered when he fell off the horseback.

Option C is incorrect because Ramesh falling off a horseback and suffers a grave injury is not the proximate cause of his death. This is because the grave injury is not the direct cause of Ramesh’s death. The direct cause of Ramesh’s death is the pneumonia, which is a secondary condition that developed as a result of the grave injury.