Final answer:
Changes in the sediment supply at the mouth, elevation at the base level, human development along the river channel, and the slope the river flows across can all initiate or terminate the life of a river.So the correct option is a.
Step-by-step explanation:
Changes in the sediment supply at the mouth, elevation at the base level,
human development along the river channel, and the slope the river flows across can significantly influence a river's existence.
Alterations in sediment supply at the river mouth impact the river's ability to deposit sediments, affecting its morphology and dynamics.
Changes in the base level's elevation, such as uplift or subsidence, can lead to the river altering its course, impacting its flow and longevity.
Human development along the river, including dams, diversions, or pollution, can disrupt its natural course, affecting ecosystems and water flow.
Additionally, the slope across which the river flows dictates its speed, erosive capacity, and ability to transport sediment.
A drastic change in slope due to natural events or human interference can fundamentally reshape the river's course or cause its cessation,
illustrating the critical role these factors play in a river's life cycle.
So the correct option is a.