Use the paragraph to answer the question.
About 1.5 million species of fungi exist on Earth. They act as nature's decomposers. These organisms break down matter and release enzymes and acids that unlock nutrients for plants and soil organisms. You may be familiar with macrofungi, a type of fungus that includes mushrooms. But for the most part, fungi exist as mycelia, tiny threads that snake underground in billions of interconnected threads. They twist and twine with tree root systems, helping tress obtain crucial nutrients. Mycologists call these networks of mycelia "Earth's nervous system."
Which statement best identifies the central idea of the paragraph?
A. The type of fungus called macrofungi includes mushrooms.
B. Fungi exist as a web of threads connected underground.
C. Fungi bring nutrients to tree root systems when they twine with them underground.
D. Earth's many species of fungi act as decomposers of matter.
D. Earth's many species of fungi act as decomposers of matter.
The central idea of the paragraph is that fungi exist as a web of threads connected underground.
The central idea of the paragraph is:
D. Earth's many species of fungi act as decomposers of matter.
To arrive at this answer, we look for the main point that is being emphasized throughout the paragraph. In this case, the paragraph begins by stating that 1.5 million species of fungi exist on Earth and then goes on to explain how they act as nature's decomposers, breaking down matter and releasing enzymes and acids to unlock nutrients for plants and soil organisms. The other statements mentioned in the paragraph (about macrofungi and the interconnected threads of mycelia) are supporting details that help provide more context to the central idea of fungi as decomposers. Therefore, option D is the best statement that identifies the central idea of the paragraph.