If all the puddles and ponds are destroyed, the entities likely to be destroyed are

The correct option is Plasmodium.

To understand why destroying puddles and ponds leads to the destruction of Plasmodium, we can examine the life cycle and transmission vector of this organism step-by-step:

1. What is Plasmodium?
Plasmodium is a genus of unicellular eukaryotes that are obligate intracellular parasites. It is the causative agent of malaria in humans and other animals.

2. The Transmission Vector:
Plasmodium requires a biological vector to transmit from one host to another. This vector is the female Anopheles mosquito. The parasite undergoes a crucial part of its sexual reproduction and development stage inside the mosquito's gut and salivary glands.

3. Link to Puddles and Ponds:
Mosquitoes, including the Anopheles species, require stagnant water bodies such as puddles, ponds, marshes, and ditches to lay their eggs. The larval and pupal stages of the mosquito's life cycle are entirely aquatic and depend on these standing water sources to mature into adult flying mosquitoes.

4. Impact of Destroying Stagnant Water:
If all puddles and ponds are destroyed or drained:
⇒ Female Anopheles mosquitoes lose their breeding grounds.
⇒ The mosquito population decreases drastically because they cannot complete their life cycle.
⇒ Without the mosquito vector, Plasmodium cannot be transmitted between hosts, interrupting its life cycle and ultimately leading to the destruction of the parasite population.

In contrast, the other options do not rely on aquatic mosquito vectors for their transmission:
• Ascaris is a roundworm transmitted primarily through the ingestion of soil or food contaminated with its infective eggs.
• Leishmania is transmitted by the bite of infected female sandflies, which breed in organic matter and damp soil, not in open pools of water.
• Trypanosoma (such as the species causing sleeping sickness) is transmitted by the tsetse fly, which breeds in warm, dry vegetation areas or forested environments rather than aquatic habitats.