Read the following passage and mark the letter A, B, C, or D to indicate the answer to each of the question.

When he was nine years old, Felix Finkbeiner gave a class presentation on climate change. The young German spoke about deforestation and its effect on the planet. At the end of his talk, he challenged the people of his country to help by planting one million trees. Nobody thought much would come of a nine-year-old’s school project. Before he was 20, however, Finkbeiner’s efforts had resulted in the planting of more than 14 billion trees around the world. Finkbeiner and his classmates began the project - named “Plant-for-the-Planet” - by planting the first tree outside their school. Other schools followed the example, and news of the one-million challenge spread. As a result, Finkbeiner was asked to speak at the European Parliament. Other invitations soon followed, and when he was just 13, he spoke at a United Nations conference in New York. “We cannot trust that adults alone will save our future,” he said in the speech. “We have to take our future in our hands.”

Finkbeiner is now in his twenties, and Plant-for-the-Planet is an organization with around 70,000 members. It works to teach people about climate change and to encourage the planting of more trees. Germany’s one millionth tree was planted long ago. The goal now is one trillion - 150 for every person on Earth.

The word "deforestation" in paragraph 1 is closest in meaning to ______.