For a position vector \(\vec r = x\hat i + y\hat j + zk\) the norm of the vector can be defined as \(\left| {\vec r} \right| = \sqrt {{x^2} + {y^2} + {z^2}}\). Given a function \(\phi = \ln \left| {\vec r} \right|\), its gradient ∇ϕ is
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\(\vec r\)
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\(\frac{{\vec r}}{{\left| {\vec r} \right|}}\)
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\(\frac{{\vec r}}{{\vec r \cdot \vec r}}\)
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\(\frac{{\vec r}}{{{{\left| {\vec r} \right|}^3}}}\)