Correct option is C. \(\vec{AB}+\vec{BC}-\vec{CA}=\vec 0\)
\(\because\) \(\vec{AB}+\vec{BC}=\vec{AC}\)
Subtracting \(\vec{CA}\) , from both the sides of the above mentioned equation,
\(\therefore
\) LHS \(\neq\) RHS
Hence, it is not true.
\(\vec{AB}+\vec{BC}-\vec{CA}\)