The sigmoid function is defined as sigmoid(x) = 1/(1+e-x). If the score is defined by 4x1 + 5x2 - 9 = score, then which of the following points has exactly a 50% probability of being blue or red? (Choose all that are correct.)
A. (1, 1)
B. (2, 4)
C. (5, -5)
D. (-4, 5)
Calculator online: https://www.vcalc.com/wiki/vCalc/Sigmoid+Function