$\text{If two parallel lines are cut by a transversal, then the pairs of alternate interior angles are:}$

• A. $\text{supplementary}$
• B. $\text{congruent}$
• C. $\text{complementary}$
• D. $\text{right angles}$

Answer: (B)

Verified step by step guidance

1. Understand the setup: Two parallel lines are cut by a transversal line, creating several angles at the points of intersection.
2. Identify alternate interior angles: These are pairs of angles that lie between the two parallel lines but on opposite sides of the transversal.
3. Recall the property of alternate interior angles when lines are parallel: They are equal in measure, meaning they have the same angle value.
4. Note that supplementary angles add up to 180 degrees, complementary angles add up to 90 degrees, and right angles are exactly 90 degrees, but alternate interior angles are not defined by these sums in this context.
5. Conclude that the pairs of alternate interior angles formed by a transversal cutting two parallel lines are congruent, meaning they have equal measures.