Which one of the following vector functions represents a magnetic field $\overrightarrow{B}$?
$\text{($\hat{X}, \hat{Y}$ and $\hat{Z}$ are unit vectors along x-axis, y-axis, and z-axis, respectively)}$
- $10x\hat{X}+20y\hat{Y}-30z\hat{Z}$
- $10y\hat{X}+20x\hat{Y}-10z\hat{Z}$
- $10z\hat{X}+20y\hat{Y}-30x\hat{Z}$
- $10x\hat{X}-30z\hat{Y}+20y\hat{Z}$