help with explaining pls

[south lichen]

x² + y² + 2xy = 1
1 + 2xy = 1
2xy = 0
xy = 0
x = 0 -> y = 1, y = -1
y = 0 -> x = 1, x = -1
x + y <= 0
so the points are (-1,0) and (0,-1)
hence 2 (B)

[tame trench]

thanks