Passage Summary: A psychologist suggests that children have to learn how to draw curved lines before they are capable of learning how to draw sharp angles.

Conclusion: The ability to copy curves is a developmental prerequisite for the ability to copy angles.

Reasoning: This hypothesis is derived from research conducted on the developmental patterns of young children.

Analysis: To strengthen a claim about a necessary sequence of development, we need evidence that the order is never reversed. The most helpful data would show that while some children can draw curves but not angles, no children can draw angles but not curves. Look for an answer choice that provides this kind of lopsided evidence, confirming that the 'curve' skill is indeed the foundation upon which the 'angle' skill is built.