If f(x,y,z)=x2yz+z3f(x, y, z) = x^2yz + z^3f(x,y,z)=x2yz+z3, what is the gradient ∇f\nabla f∇f at (1,1,1)(1, 1, 1)(1,1,1)?
⟨1,1,4⟩\langle 1, 1, 4 \rangle⟨1,1,4⟩
⟨2,1,4⟩\langle 2, 1, 4 \rangle⟨2,1,4⟩
⟨3,1,1⟩\langle 3, 1, 1 \rangle⟨3,1,1⟩
⟨1,2,3⟩\langle 1, 2, 3 \rangle⟨1,2,3⟩