Which of the following statements is true? a. the nitrogen cycle is the most important cycle for life. b. the oxygen cycle is the least important cycle for life. c. life can be sustained without any of the cycles for life present. d. all cycles of matter are equally important for life to be sustained.

The right option is d. All cycles of matter are equally important for life to be sustained.

All the cycles of matter including carbon cycle, water cycle, nitrogen cycle, phosphorus cycle, and sulfur cycle are equally important for life to be sustained. Limited amount of matter are available on earth and their cycling ensure the continuous survival of all living organisms. Carbon is an essential element as it is responsible for building all organic matter. Phosphorus and sulfur are also found within every organism .

currents is the correct answer.