Weeds which produce light and numerous seeds are normally dispersed by

Weeds that produce a large number of seeds and are light in weight are usually dispersed by wind. This means that the seeds are carried away from the parent plant by the movement of air.

When weeds produce many seeds, it increases their chances of survival and spread. The wind helps in dispersing the seeds over a larger area, allowing them to find suitable conditions for germination and growth.

The light weight of the seeds enables them to be easily carried by the wind. As the wind blows, it carries the seeds with it, often over long distances. This allows the seeds to reach new locations where they can establish themselves and compete with other plants for resources such as sunlight, water, and nutrients.

In contrast, water dispersal (Option B) is more common for plants that grow near bodies of water, such as rivers, lakes, or oceans. These plants have seeds that are adapted to float on water and be carried away by currents. Animals (Option C) and insects (Option D) can also be involved in seed dispersal, but they are not the main method for weeds that produce light and numerous seeds.

So, the correct answer to this question is Option A: wind.