Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 34 to 38.

Initially seen purely as centres of entertainment, zoos were often heavily criticised in society for keeping animals captive. Nowadays, however, zoos have a lot more to offer than perhaps some people realise. Good zoos have changed their focus and are now ___(1)___ to environmental problems, such as the decline in wildlife and loss of habitat. Indeed, scientists believe that a third of ___(2)___ animal and plant species on Earth risk extinction within this century.
The modern zoo, ___(3)___, has developed dramatically as a major force in conserving biodiversity worldwide. Zoos linked with the Association of Zoos and Aquariums participate in Species Survival Plan Programmes, ___(4)___ involve captive breeding, reintroduction programmes and public education to ensure the survival of many of the planet's threatened and endangered species.
Captive breeding is the process of breeding animals outside their natural environment in ___(5)___ conditions such as farms, zoos or other closed areas. It is a method used to increase the populations of endangered species, in order to prevent extinction. One of the main challenges facing captive breeding programmes, however, is maintaining genetic diversity.