Final answer:
The point-slope equation for Zellie's position on the stairs at 2 minutes and 100 steps from the bottom is B) y - 100 = m(x - 2). This equation uses the point-slope format with the given point to describe her position change over time.
Step-by-step explanation:
The correct point-slope equation representing Zellie's position on the stairs at 2 minutes, given that she was 100 steps from the bottom floor, is B) y - 100 = m(x - 2), where y is her position in steps and x is the time in minutes.
The equation is derived from the point-slope form of the line, which is y - y₁ = m(x - x₁), where m is the slope of the line. The slope, m, represents how much Zellie's position changes with respect to time, and it can be found using two widely separated points on the stair graph if it's available.
After determining the slope, we can plug it into the point-slope equation using the given point (2, 100) where 2 minutes is our x₁ and 100 steps is our y₁.