Which of the following is a common breeding site for the mosquitoes that transmit Dengue?

The correct answer is stagnant water because this type of water provides an ideal environment for mosquito breeding, particularly for species such as Aedes aegypti and Aedes albopictus, which are known vectors for the Dengue virus. These mosquitoes prefer to lay their eggs in small containers or areas where water is present but not moving.

Stagnant water can accumulate in various places around urban and peri-urban settings, including flower pots, discarded tires, puddles, and clogged gutters, making it a common breeding ground. The presence of stagnant water allows for both egg development and larval growth, essential phases in the mosquito life cycle.

In contrast, fast-moving rivers, ocean waters, and swamps do not typically provide the appropriate conditions for mosquito reproduction, as strong currents and saline environments are not conducive to the needs of mosquito larvae. Thus, stagnant water stands out as the key breeding site relevant to the transmission of Dengue fever.