Which rule relates the age of a fetus to its length for estimating growth?

The correct answer is Morrison's rule, which establishes a correlation between the length of a fetus and its age. This rule is particularly useful in forensic medicine for estimating fetal age based on measurable lengths such as crown-rump length. The principle behind Morrison's rule is that there is a predictable growth pattern during gestation, allowing medical professionals and forensic experts to infer the age of a fetus based on its length.

The other options do not pertain specifically to the relationship between fetal growth and length. Hasse's rule is often associated with different aspects of fetal measurements, while Puppe's rule typically deals with forensic psychiatric evaluations rather than fetal development. Marshall's rule is not recognized in this context of fetal size and age, making Morrison's rule the most relevant and applicable for estimating fetal growth.