An aircraft component is fabricated from an aluminum alloy that has a plane strain fracture toughness of 40 . For an applied stress of 300 MPa, what size of sharp crack will propagate until fracture and failure? Assume the crack is located on the edge of a large specimen, use a geometry factor of 1.1

A. 4.6 mm
B. 2.3 mm
C. 2120 mm
D. 5.8 mm