recall that photosynthetic rates remain relatively constant in regions near the equator. imagine that tropical environments persist throughout earth's northern and southern hemispheres; that is, that earth's entire climate mirrors that near the equator. if keeling had collected his atmospheric co2 data on such an earth, what would you expect the keeling curve to look like? please choose the correct answer from the following choices, and then select the submit answer button. answer choices a straight line sloping upward, indicating that atmospheric co2 levels would not seasonally oscillate, but would increase over time a straight line sloping downward, indicating that atmospheric co2 levels would not seasonally oscillate, but would decrease over time a straight line without a slope, indicating that atmospheric co2 levels would have remained constant over time a sinusoidal curve sloping upward, indicating that atmospheric co2 levels would fluctuate seasonally, but would increase over time a sinusoidal curve sloping downward, indicating that atmospheric co2 levels would fluctuate seasonally, but would decrease over time