Explanation:

- The phrase "exceptions" is the best fit for the blank because it suggests that while most cases follow a pattern, there are certain instances that deviate from it. In the context of life development from childhood, most children develop predictable adult traits, but there could be anomalies.

- Exceptions suggest rare cases where the expected outcome doesn't happen. This aligns with the idea of unpredictable changes, like a "bright morning may end in a storm."

- "Concessions" refers to compromises which doesn't fit the idea of life unpredictability in this context.

- "Exemptions" are exclusions from a rule or condition, which doesn't fit because the context is about natural growth, not administrative processes.

- "Rejections" imply a refused or denied condition, which doesn't relate appropriately to life’s unpredictable nature.

The correct option to fill in the blank is option 3: exceptions.