stress concentration factor in elliptical hole

Question

In a semi – infinite flat plate shown in the figure the theoretical stress concentration factor for an elliptical hole of major axis 2a and minor axis 2b is given by

(a) K_i = a/b

(b) K_i = 1 + a/b

(c) K_i = 1 + 2b/a

(d) K_i = 1 + 2a/b