Answer:
She was young yet carried herself with great confidence, and her clear eyes locked onto mine and oozed kindness.
Explanation:
The second option states she knew she would like the dentist and would never be so anxious again, but it isn't a 'descriptive image that helps explain <em>why</em> Rachel feels comforted.' Generally, when we see a person close to age engaging in an activity that would otherwise make us nervous, we involuntarily relax -- because if they're cool, why wouldn't we be too, so the second option is probable, but not everyone is aware that our brains work that way.
The first option, though, clearly and descriptively gives Rachel a reason to be kind -- the dentist's eyes are kind and clear.
