Introduction:
Prosopis juliflora is a plant species that has recently been in the news. It is important to understand the characteristics and impacts of this plant species to determine its categorization. In this case, the correct answer is option 'A' - Prosopis juliflora is an invasive plant.

Invasive Plant:
An invasive plant is a species that is non-native to a specific ecosystem and has the potential to spread rapidly, outcompeting native species and causing ecological and economic harm. Invasive plants often lack natural predators or diseases that would otherwise control their population growth. Consequently, they can disrupt the balance of the ecosystem and negatively affect biodiversity.

Characteristics of Prosopis juliflora:
Prosopis juliflora, commonly known as mesquite or mesquite tree, is a fast-growing shrub or small tree native to Central and South America. It has been widely introduced in various parts of the world, including Africa, Asia, and Australia, primarily for its ability to tolerate dry and harsh environments. However, due to its aggressive growth and spread, it has become a major invasive species in many regions.

Impacts of Prosopis juliflora:
1. Ecological Impact: Prosopis juliflora has a high reproductive capacity and can produce numerous seeds that are dispersed by wind, water, and animals. These seeds can germinate easily, leading to the formation of dense and impenetrable thickets. These thickets can outcompete native plant species for resources such as light, water, and nutrients, reducing biodiversity and altering the composition of the ecosystem.

2. Economic Impact: The invasion of Prosopis juliflora can have severe economic consequences. It competes with native vegetation, making it difficult for farmers to cultivate crops or graze livestock. The plant's dense growth also hampers access to water sources, reducing water availability for both humans and animals. Additionally, the thorns of Prosopis juliflora can cause injuries to humans and animals.

3. Social Impact: The invasion of Prosopis juliflora can have social implications as well. Local communities that rely on natural resources may suffer from reduced access to grazing lands, firewood, and other ecosystem services. This can lead to increased poverty and food insecurity, particularly in rural areas where subsistence agriculture is prevalent.

Conclusion:
In conclusion, Prosopis juliflora is categorized as an invasive plant due to its ability to spread rapidly, outcompete native species, and cause ecological, economic, and social harm. Efforts should be made to control and manage the spread of this invasive species to mitigate its negative impacts on ecosystems and livelihoods.