Canals have been present in human construction and architecture for many centuries. Beginning in ancient times, the Romans and even before them civilizations used these architectural structures to ensure the easy passage of water from one place to another without having to transport the water. They also ensure the easier passage of transport means like boats and ships, cutting through territories of land that are surrounded by water and roads cannot be constructed, like is the case of cities like Venice. In recent times, however, with the increase of technology, humans learned to makes these canals bigger and deeper, connecting bodies of water through wich large cargo ships can go. One such example is the Panama Canal. The exact definition of a canal is: A channel or watercourse that allows for navigation or the draining of land. The correct answer then is D. Canals are ditches filled with water that are man made.