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 from 28 to 34.

Humans are consuming hundreds of wild animals “to extinction” for meat, ornaments, medicines and pets, according to scientists. A global crisis sparked by unregulated or illegal hunting and trapping means 301 different species - from monkeys to bats - are now in danger, a new study claims. Experts at Oregon State University in the US, who conducted the research, have warned the decline is having a significant environmental impact and undermining the food security of millions of people in Asia, Africa and South America. “Our goal is to raise awareness of this global crisis. Many of these animals are at the brink of extinction. The illegal smuggling in wildlife and wildlife products is run by dangerous international networks and ranks among trafficking in arms, human beings and drugs in terms of profits,” said study leader Professor William Ripple.

Researchers concluded that bold changes and political will were needed to diminish the possibility of humans consuming many of the world’s wild mammals to the point of extinction. Of the species affected, 126 were primates, more than any other group, according to a team of researchers writing in the journal Royal Society Open Science. Animal rights activists said the study should serve as a wake-up call to protect endangered species from extinction. “This research should be heart-stopping news for anyone who cares about wild animal welfare and the health of our planet. Urgent action needs to be taken by governments across the globe to protect these hundreds of threatened species from extinction,” Dr Neil D’Cruze, Head of Wildlife Research and Policy at World Animal Protection told The Independent.

The authors found that wild meat made up a crucial part of global diets, with an estimated 89,000 tonnes harvested annually in the Brazilian Amazon alone. They also found overhunting to be mainly associated with poorer countries, where hunters might find it harder to feed their families. The research also showed much of the wild animal meat was sold in street markets and destined to become urban restaurant delicacies.

In 2010, another study found that about five tonnes of bushmeat was smuggled weekly in tourist luggage through Charles de Gaulle airport in Paris, France. Dr D’Cruze said: “There are also the too often forgotten welfare impacts and high levels of suffering that animals, like primates, endure when captured and slaughtered for bush meat or the illegal wildlife trade. We must prevent the extinction of these incredible species, but we must also eradicate the pain and suffering being inflicted on millions of animals as we speak.” Large carnivores and herbivores over 10 kg comprised a small percentage of the animals listed but were hit more severely by overhunting, it was claimed. Scientists also warned the loss of large mammals could result in population explosions of prey animals, greater risk of disease and economic impact on humans. The study found that 57 large species of even-toed ungulates, including hippopotamus, wild yak, camel and marsh deer, were threatened by hunting. Smaller mammals were said to play crucial roles in dispersing seeds, pollinating plants and controlling insects. Wild ox, camels, pigs, fruit bats, rhinoceroses, tapirs, deer, tree kangaroos, armadillos, pangolins, rodents and big cats, were all said to be affected.

(Soure: https://www.independent.co.uk)

According to paragraph 4, all of the following are the essential roles that small animals play EXCEPT?

Petroleum is composed of a complex mix of hydrogen and