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

Trees provide us with (34) _____ valuable resources such as building materials, fuel, rubber, and food. They also provide essential shelter for people, animals, and other plants as well as reducing the devastating effects of flooding (35) _____ can make whole communities of people and animals homeless.
Most importantly, though, they protect the world's climate by absorbing massive amounts of harmful chemicals, such as carbon dioxide, from our atmosphere and in turn give off oxygen. Without trees, there would be no (36) _____ of minimising the effects of global warming caused by the Greenhouse Effect.
(37) _____, trees are a constant source of medicine. Unfortunately, tropical forests are disappearing at an alarming (38) _____ and man must act soon to protect our most valuable natural resource.