# If $\overrightarrow v=2\hat i+\hat j-\hat k\:\:and\:\;\overrightarrow w=\hat i+3\hat k$ and $\overrightarrow u$ is a unit vector,then the maximum value of $[\overrightarrow u\:\overrightarrow v\:\overrightarrow w]$ is ?
$(A)\;-1 \\ (B)\;\sqrt {10}+\sqrt 6\\ (C)\;\sqrt {59}\\(D)\;\sqrt {60}$