# $\overrightarrow{r}=s\overrightarrow{i}+t\overrightarrow{j}$ is the equation of

$\begin{array}{1 1}(1) a\; straight \;line\; joining\; the\; points \overrightarrow{i} and \overrightarrow{j}&(2)x\;o\;y \;plane\\(3)y\;o\;z\;plane&(4)z\;o\;x\;plane\end{array}$

The vector equation of a plane passing through a point with position vector $\overrightarrow{a}$ and parallel to the vector $\overrightarrow{u}$ and $\overrightarrow{v}$ is
$\overrightarrow{r}=\overrightarrow{a}+s\overrightarrow{u}+t\overrightarrow{v}$
The vector equation of the plane passing through the origin $\overrightarrow{a}=0 \overrightarrow{i}+0 \overrightarrow{j}+0 \overrightarrow{k}$ and parallel to the vector $\overrightarrow{i}$ and $\overrightarrow{j}$ is
$\overrightarrow{r}=(0 \overrightarrow{i}+0 \overrightarrow{j}+0 \overrightarrow{k} )+s\overrightarrow{i}+t\overrightarrow{j}$
$\overrightarrow{i}$ and $\overrightarrow{j}$ are the vectors lying in the x o y plane.
Hence 2 is the correct answer