Questions: Premature babies may have trouble breathing because Their lungs are too small They forget to breathe Their voice box has not formed yet They do not produce enough surfactant

The answer is the fourth one: they do not produce enough surfactant.

Explanation for each option:

1. Their lungs are too small: While premature babies do have underdeveloped lungs, the primary issue with breathing is not the size of the lungs but the lack of surfactant.
2. They forget to breathe: This can be a problem in some premature babies (a condition known as apnea of prematurity), but it is not the main reason for breathing difficulties.
3. Their voice box has not formed yet: The voice box (larynx) is not directly related to the ability to breathe. It is more involved in producing sound.
4. They do not produce enough surfactant: Surfactant is a substance that helps keep the air sacs in the lungs open by reducing surface tension. Premature babies often have insufficient surfactant, leading to respiratory distress syndrome (RDS).

Summary: Premature babies may have trouble breathing primarily because they do not produce enough surfactant, which is crucial for keeping their lungs' air sacs open and functional.