Final answer:
The best description of the relationship between the triangles is that they are similar if they have three pairs of congruent angles, as this ensures similarity by the Angle-Angle criterion.
Step-by-step explanation:
The question relates to the conditions for triangle similarity. Two triangles are considered similar if they satisfy the Angle-Angle (AA) similarity criterion, which states that two triangles are similar if they have two pairs of congruent angles. The presence of three pairs is not necessary since the third pair will automatically be congruent because of the fact that the sum of angles in a triangle is 180 degrees. Thus, the correct statement is that triangles are similar if they have two pairs of congruent angles, which would be sufficient to assert similarity.
However, from the given answer choices, the best option that could be selected in an exam context considering that two congruent angles ensure the third one is also congruent is option 1: The triangles are similar because they have 3 pairs of congruent angles.