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 26 to 30.

Tourism is now one of the largest industries in the world, and is the main source of income in (26) _______ countries. It may bring in earnings, create jobs for local people and improve their life as a whole. Unfortunately, the construction of essential facilities to (27) _________ the increasing need of visitors has destroyed natural habitats, thus threatening wildlife and spoiling some of the world's most beautiful regions. Air travel to distant places results in huge amounts of carbon emissions (28) _________ contribute to global warming.

The majority of holidaymakers are unaware of such issues, (29) ________ fortunately there are people who would rather travel with environmental responsibility. For these travellers, there is now an alternative to conventional tourism, known as ecotourism. They choose their travelling carefully, and try to make sure that their visit will have only a (30) _________ effect on the environment.

(Adapted from Master Mind)