Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.

Today, wild animals and the wild places where they live are seriously threatened almost everywhere. One species has become extinct in each year of this century. But many hundreds are now in danger. The speed of the extinction of species has been faster than ever before. Hunting is no longer the major cause of mass extinction, although rare birds and animals continue to be butchered for their skin,  feathers,  tusks,  and internal organs, or taken as savage pets.  The main

reason of the extinction comes from the destruction of the natural habitat where

wild plants, animals, and insects need to survive. As a result,  many species of animals, birds, and even insects are at risk of disappearing from the Earth. The draining and damming of wetland and river courses threatens the aquatic food chain and our own seafood industry. Overfishing and the destruction of fragile coral reefs destroy ocean biodiversity. Deforestation has caused serious damage to natural habitat which animals rely on to survive,  particularly in the tropics which the most global biodiversity is at stake in. The immense tropical forests that are known as the lungs of the earth are being destroyed by human activities such as building hydroelectric dams across rivers, agricultural cultivation,... ect, such species disappear forever.

Which is no longer considered a major cause of the mass extinction ?