# Two sides of a rhombus are along the lines, $x−y+1=0$ and $7x−y−5=0$. If its diagonals intersect at $(−1, −2)$, then which one of the following is a vertex of this rhombus ?
$( A ) (-3, -9)$
$( B ) (-\frac{10}{3}, -\frac{7}{3})$
$( C ) (-3, -8)$
$( D ) (\frac{1}{3}, -\frac{8}{3})$