The correct answer is c) Nile perch.

Explanation:
The extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in Lake Victoria of East Africa was primarily caused by the introduction of the Nile perch (Lates niloticus). Here is a detailed explanation of why the Nile perch led to the extinction of these cichlid fish species:

1. Introduction of Nile Perch: In the 1950s, the Nile perch, a large predatory fish native to the Nile River, was introduced into Lake Victoria as a part of a commercial fishery program. The introduction was aimed at boosting the local economy and providing a new source of income for the region.

2. Predatory Behavior: The Nile perch is a voracious predator and has a broad diet, feeding on a variety of fish species, including the cichlids found in Lake Victoria. The introduction of this apex predator disrupted the balance of the ecosystem, as the cichlids were not adapted to predation by such a large and efficient predator.

3. Competitive Advantage: The Nile perch quickly established itself as a dominant species in Lake Victoria due to its predatory prowess, high reproductive rates, and ability to exploit a wide range of food resources. It outcompeted the native cichlid fish for resources such as food and breeding sites, leading to a decline in the cichlid populations.

4. Habitat Destruction: The Nile perch's feeding behavior also contributed to habitat destruction. As it preyed upon the cichlid fish, it caused a decrease in their populations. This led to a reduction in their grazing activities and resulted in an overgrowth of aquatic vegetation, altering the habitat structure and reducing the availability of suitable breeding sites for cichlid fish.

5. Reproductive Isolation: The cichlids in Lake Victoria had evolved into numerous species with unique adaptations to different ecological niches, resulting in a high level of species diversity. However, the introduction of the Nile perch disrupted the natural reproductive isolation mechanisms of the cichlids. The predation pressure from the Nile perch led to hybridization and genetic assimilation, causing the loss of distinct cichlid species.

6. Loss of Biodiversity: The extinction of the cichlid fish species in Lake Victoria is considered one of the most significant examples of human-induced extinctions in recent history. This loss of biodiversity has had cascading effects on the entire ecosystem, including changes in the food web, nutrient cycling, and ecosystem stability.

In conclusion, the introduction of the Nile perch into Lake Victoria led to the extinction of more than 200 species of cichlid fish. The predatory behavior of the Nile perch, along with its competitive advantage and disruption of reproductive isolation mechanisms, caused a decline in cichlid populations and altered the ecological dynamics of the lake.