consider the diagram. lines a and d are non - coplanar. parallel. perpendicular. skew.

Answer

Explanation:

Step1: Recall definitions

Coplanar lines lie in the same plane. Parallel lines are coplanar and never intersect. Perpendicular lines are coplanar and intersect at a right - angle. Skew lines are non - coplanar and do not intersect.

Step2: Analyze the diagram

Lines a and d are not in the same plane and do not intersect.

Answer:

skew