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 19 to 23.

Global warming is the rise in the average temperature of the earth (19) _____the increase of greenhouse gases. Climate scientists now believe that (20) ______ are mainly responsible for this. The burning of fossil fuels and the cutting down of large areas of forests have contributed to the (21) _______ of a large amount of harmful gases into the atmosphere in recent years. The thick layer of these gases traps more heat from the sun, which leads to the increase in the earth’s temperature.

Global warming (22) _______climate change and catastrophic weather patterns such as heat waves, floods, droughts, and storms, which can affect human lives. Hundreds of millions of people may suffer (23) _____ famine, water shortages, and extreme weather conditions if we do not reduce the rate of global warming.

Global warming is the rise in the average temperature of the earth (19) _____the increase of greenhouse gases.