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Please explain this ques

The magnitude of the vector is 15 units.

So,

$\sqrt{{\left(5\sqrt{3}\right)}^{2}+{\left(5\sqrt{3}\right)}^{2}+{\left(5\sqrt{3}\right)}^{2}}=\sqrt{75+75+75}=\sqrt{225}=15units.\phantom{\rule{0ex}{0ex}}$

Also,

the angle made by the vector with x and z axis are same. So, the x- and z-component of the vectors must be same.

Looking into the options, we found

Option (A) is the CORRECT answer.

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