Parallel Lines: Numbering in the drawing

To solve this problem, we'll examine the provided figure to determine which sides are parallel.

Based on the diagram:

• The side $AB$ is opposite side $DC$, and they are aligned horizontally and parallel to each other.
• Similarly, the side $BC$ is opposite side $AD$, and they are aligned vertically and parallel to each other.

This analysis indicates that the quadrilateral depicted is a rectangle, where opposite sides are parallel.

Therefore, the parallel sides are $AB \parallel DC$ and $BC \parallel AD$.

This confirms the correct choice from the options given.

Therefore, the solution to the problem is $AB||DC$ and $BC||AD$.