Consider a single crystal of some hypothetical metal that has an FCC crystal structure and is oriented such that a tensile stress is applied along a[102] direction. If slip occurs on a( 111) plane and in a [ 101] direction, compute the stress at which the crystal yields if its critical resolved shear stress is 12.76 MPa. 
a. 13.96 MPa  
b. 52.1 MPa  
c. 0 MPa  
d. 30.9 MPa  
e. 3.1 MPa