The correct option is C Increase in the volume of water in a tank.
Growth is a fundamental characteristic of living organisms. It is defined as the irreversible, permanent increase in the size of a part or whole of the organism. It is preceded by metabolic processes occurring at the expense of energy. There is no role of any metabolic process or energy usage in mountain height, soaked wooden plank, and water in the tank. Hence, none of the given instances is an example of growth. Expansion of leaves or increase in the weight of a toddler are examples of growth. Both the incidences occur due to metabolic processes like respiration and transport of food with the help of energy usage.