a) PQ | RT;

This question appears to be a statement from a geometry problem, likely indicating that line segment PQ is parallel to line segment RT. However, without the full context of the problem or a diagram, it's impossible to provide a specific answer or solution. It could be a premise for further deductions in a geometry proof or problem-solving task.

Possible interpretations:

• PQ || RT (PQ is parallel to RT)
• PQ ⊥ RT (PQ is perpendicular to RT) - if the symbol '|' represents perpendicularity in this context.

To provide a definitive answer, please provide the complete problem statement or an image of the accompanying diagram.