Final answer:
Hierarchical proportion is not unusual in Egyptian art and is observed in the larger depiction of more significant figures. Egyptian art also commonly uses composite figures, combining profile and frontal perspectives to convey completeness.
Step-by-step explanation:
The question asks what aspect of a relief is not unusual in Egyptian art. Among the options given, hierarchical proportion would be the aspect that is not unusual. In Egypt's artistic canon, there are several characteristics that are considered standard, and these include using hierarchical scales to denote importance, symbolic representation, and the use of composite figures. For instance, more significant figures would often be depicted as larger than less important ones in a hierarchical fashion. Furthermore, Egyptian art often employed composite figures, with a unique combination of profile and frontal perspectives - heads would be shown in a profile view while shoulders and eyes were often rendered frontally. This stylistic convention provided a comprehensive view of each figure. While naturalism did appear to some extent, especially during the Late Period, it was not as prevalent as the stylized formalism that characterized much of Egyptian art.