ds1

[stubbornp]

ds1

[Morgoth]

Statement (1)
slope of line k is negative.
Since the line passes through the origin, the line will be drawn from bottom right to top left, therefore b can be positive if a,b lies in the second quadrant, b could also be negative if a,b lies in the fourth quadrant. Insufficient.

Statement (2)
a<b, same reasoning as above. Insufficient.

Combining (1) & (2)

we know in second quadrant a<b, slope is negative, therefore b is positive. Sufficient.

Thus, C.

OA?

[stubbornp]

oa C....