Task: Question Answering
Input (English): Question: In the xy-coordinate plane, the graph of y = -x^2 + 9 intersects line L at (p,5) and (t,7). What is the least possible value of the slope of line L?

 Option A: 6

 Option B: 2

 Option C: -2

 Option D: 1

 Option E: -10
Output (English): Option D