Consider a Boolean function f(w,x,y,z). Suppose that exactly one of its inputs is allowed to change at a time. If the function happens to be true for two input vectors i₁=⟨w₁,x₁,y₁,z₁⟩ and i₂=⟨w₂,x₂,y₂,z₂⟩ , we would like the function to remain true as the input changes from i₁ to i₂ (i₁ and i₂ differ in exactly one bit position) without becoming false momentarily. Let f(w,x,y,z)=∑(5,7,11,12,13,15) . Which of the following cube covers of f will ensure that the required property is satisfied?

• A. w’xz, wxy’, xy’z, wyz
• B. wxy, w’xz, wyz
• C. wxy’z’, xz, wx’yz
• D. wxy’,wyz,wxz,w’xz,xy’z,xyz