My answer is A
1. As the line doesn't intersect the line the line is parallel to l, so the slopes will be same
Statement 1 alone sufficient
2. As line intersect l, the line is not parallel. We can not derive slope of line l.

The question is not clear .. Is this DS a question ?

Here the line l is parallel to the line y=1-x and hence the slope should be negative

The answer as said by nilesh is indeed A.

Solution:-
Concepts Required:
1. The simplest of an equation of a line is y = mx + c
where m is the slope and c is the intercept on y-axis (i.e. the point at which the line meets the y-axis)
2. Parallel lines have same slope.
3. If 2 or more lines do not intersect then they are parallel lines.

Since this is a DS question and we have to find the slope of the line l.

Option 1
We know that l and l' (assume l' => y=1-x) are parallel. hence slope of l and l' are the same.
l' can be rewritten as y = (-1)*x + 1;
hence from the equation of line slope = -1.
Option 1 is sufficient.

Option 2
Lines l and l"(assume l" => y=x-1) intersects. Using this information we can only know that the line l and line l" have one point in common, which again has infinite possibilities.
Hence this is insufficient information.

Therefore Option 1 alone is sufficient to answer the problem and not option 2.