$2.()$ at $\backslash (\backslash$mathrm$\{$t$\}=0\backslash ),$ the stator's voltage at phase a is $30$ degrees, what is the phase angle of the current

$($I$)$ and the magnetic field $($B$)?$

A$.30$ and $-60$

B$.30$ and $30$

C$.-60$ and $30$

D$.30$ and $-60$