Answer:
Third option: Lines "r" and "s" and lines "t" and "u" must be parallel.
Step-by-step explanation:
The missing figure is attached.
You need to remember that:
1- A Transversal is defined as a line that intersects two or more lines.
2- When a transversal cut two parallel lines, several angles are formed, which are grouped in pairs. Some of them are:
a. Vertical angles: are those pairs of angles that share the same vertex and are opposite to each other. These angles are congruent.
b. Corresponding angles: are those pairs of non-adjacent angles located on the same side of the transversal and outside the parallel lines. They are congruent.
In this case, you can identify in the figure that:
and
are Corresponding angles.
and
are Vertical angles.
Therefore, based on the explained before, you can conclude that lines "r" and "s" and lines "t" and "u", must be parallel.
