The evolution of oxygenic photosynthesis marked a significant change in Earth history that led to permanent changes in the redox state of Earth's atmosphere and had lasting impacts on Earth's organisms. Which of the following best describes when the evolution of oxygenic photosynthesis occurred relative to the Cambrian Explosion?

W) One billion years after the Cambrian Explosion

X) The same time as the Cambrian Explosion

Y) Two billion years before the Cambrian Explosion

Z) Three billion years before the Cambrian Explosion
Y) TWO BILLION YEARS BEFORE THE CAMBRIAN EXPLOSION