Final answer:
Participants are more likely to do well in comparing algebra problems due to the use of mental models. So, the correct answer is option a) mental models.
Step-by-step explanation:
When asked to compare algebra problems to each other and think about their common underlying structure, participants are more likely to do well due to the use of mental models. Mental models are a mental shortcut in the form of a general problem-solving framework. They help students develop a core understanding and intuition for algebra problems. By using mental models, students can focus on learning the concept expressed by an equation rather than treating equations as algorithmic tools to be memorized.