# A vector $a\hat i+b\hat j+c\hat k$ is such that its magnitude is $|a|+|b|+|c|$. This is possible only if
$(a)\:a=b=c=0\:\:\qquad\:\:(b)\:any\:two\:of\:a,b\:and\:c\:are\:zero\:\:\qquad\:\:(c)\:any\:one\:of\:a,b,c\:is\:zero\:\:\qquad\:\:(d)\:a+b+c=0$