Final answer:
The research question based on a clinical problem is the relationship between hours of bright light and irritability of preterm infants, as it seeks to explore a medical hypothesis with a specific patient group.
Step-by-step explanation:
The example of a research question based on a clinical problem is d. Relationship between hours of bright light and irritability of preterm infants.
This is because it poses a clear investigable query about a specific medical intervention's effect on a defined patient population.
In contrast, the other options provide anecdotal evidence or personal experiences, which, while valuable, do not constitute a research question designed to investigate a hypothesis through methodical inquiry.