Chloe reads that given the correct conditions, cuttings from certain plants will form roots along the stem, enabling a new plant— identical to the parent plant—to grow. Chloe wants to investigate whether rooting hormone is beneficial or detrimental in this process. She takes cuttings from a shrub. For Group 1, she places some shrub cuttings in potting soil in partial shade. For Group 2, she dips some shrub cuttings in rooting hormone, places them in potting soil, covers them with a clear dome, and places them in direct sunlight. She waters the groups equally. She pulls up some cuttings after 3 days and again after 6 and 9 days to observe and measure root growth.

Our planet has experienced five major extinctions in the four billion year history of life. the first, 450 million years ago, occurred shortly after the evolution of the first land-based plants and 100 million years after the cambrian explosion. the second extinction occurred 350 million years ago, causing the formation of coal forests. next earth experienced two mass extinctions during the triassic period, between 250 and 200 million years ago. the fifth mass extinction occurred 65 million years ago, ending the reptilian dominance of the earth. according to richard leakey, the sixth mass extinction is happening right now. leakey suggests that we, the human race, are the cause. each year, at our hand, approximately 50,000 species vanish from earth. he believes that man is destroying earth at a rate comparable with the impact of a giant asteroid. leakey's statistics indicate that 50% of earth's species will become extinct within the next 100 years assuming leakey's hypothesis of a sixth mass extinction to be true, how will we expect the model to change? a) a sharp spike in the graph approximately 100 million years from now b) a dip in the graph, followed by a sharp spike about 100 million years from now c) a sharp spike in the graph immediately following the "0" location of the x axis d) a plateau following the "0" mark on the x axis, followed by a gradual rise to a new peak