Which one of the following vector functions represents a magnetic field $\overrightarrow{B}$?

$\text{($\hat{X}, \hat{Y}$and$\hat{Z}$are unit vectors along x-axis, y-axis, and z-axis, respectively)}$

1. $10x\hat{X}+20y\hat{Y}-30z\hat{Z}$
2. $10y\hat{X}+20x\hat{Y}-10z\hat{Z}$
3. $10z\hat{X}+20y\hat{Y}-30x\hat{Z}$
4. $10x\hat{X}-30z\hat{Y}+20y\hat{Z}$