Opposite sides of rhombus are parallel. So their ratios are equal as...
ax+by+c=0
Px+qy+r=0
a/p =b/q then lines are parallel
a/p =b/q =c/r then lines are coincident
Now AD eqn is x+y=1
So it's parallel line BC eqn would be x+y=k
Where k ! =1 otherwise AD and BC would be coincident so
Option 2 and 3 not possible.
And intersecting point of both diagonals is origin so rhombus equally divided by axes
Option 1 can be possible