If 2 lines are parallel then:
they determine a plane, that is they are coplanar. In this plane, they never intersect.
A) they intersect at a single point : Not True, they never intersect.
B) they are perpendicular: Not true, they are parallel...
C) the are skew lines : Not true, "skew" is the opposite of "coplanar". 2 lines are skew means that they are not on the same plane. But we mentioned that 2 parallel lines are always on the same plane.
D) they are coplanar: True
Answer: D