The correct answer is option 4: Underground water may also be connected to surface water.

Option 1 is incorrect. Transpiration by plants is an essential part of the water cycle. It is the process by which plants release water vapor into the atmosphere, which can contribute to the formation of clouds.

Option 2 is also incorrect. While evaporation of surface water from rivers and oceans plays a significant role in cloud formation, it is not the only factor. Other sources of moisture, such as transpiration from plants and evaporation from lakes and streams, also contribute to cloud formation.

Option 3 is incorrect. Rainfall is a crucial component of the water cycle and plays a critical role in replenishing the underground water table. When it rains, some water infiltrates into the soil and recharges the groundwater, maintaining the water table.

Option 4 is correct. Underground water and surface water are interconnected. Water can flow between the underground aquifers and surface water bodies like rivers, lakes, and streams through various paths such as underground channels, fractures, or permeable rock layers. This connection allows for the exchange of water between the two systems, influencing water availability and quality in both.