If the straight lines $x=1+s,\;y = -3 -\lambda s, \; z = 1 + \lambda s$ and $x= \frac{t}{2},\; y=1+t,\;z=2-t$ with parameters s and t respectively, are co-planar then $\lambda$ equals

Question

( A ) $-\frac{1}{2}$
( B ) $-2$
( C ) $0$
( D ) $-1$