Final answer:
The nunnery at Chichen Itza best fits the description of a feature not exclusively in the central Mexican style, displaying strong Puuc influences rather than central Mexican. The Temple of Kukulcan, the Great Ball Court, and the Observatory generally conform more closely to central Mexican architectural styles.
Step-by-step explanation:
The question asks which feature at Chichen Itza is not absolutely in the central Mexican style. The nunnery (Las Monjas) at Chichen Itza is the structure that best fits this description, as it embodies a variety of styles less central to central Mexican architecture. Most notably, the nunnery shows strong Puuc influences - a Maya architectural style that is not typically central Mexican.
Chichen Itza's other remarkable structures, including the Temple of Kukulcan (also known as El Castillo), the Great Ball Court, and the Observatory, generally conform more closely to central Mexican styles.
The Temple of Kukulcan at Chichen Itza, built between 800 to 900 CE, is an iconic pyramid featuring stairways that align with the equinoxes to cast shadows reminiscent of a serpent, which is important symbolically to both Maya and central Mexican cultures.