Which of the following is the most important cause for animals and plants being driven to extinction?

Destruction of Habitat – It is currently the biggest cause of current extinctions. Deforestation has killed off more species than we can count. Whole ecosystems live in our forests. It is predicted that all our rainforest can disappear in the next 100 years if we cannot stop deforestation.
Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment (suspected of being one of the major causes of speciation),and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species.