Polycyclic Aromatics:
Polycyclic arenes are organic compounds that contain multiple fused aromatic rings. These compounds are commonly found in coal tar, crude oil, and other fossil fuels. They have diverse applications in the pharmaceutical, agrochemical, and material industries. Understanding the structure and properties of polycyclic arenes is important for studying their reactivity and potential applications.

The Simplest Example of Polycyclic Aromatics:
Among the given options, naphthalene is the simplest example of a polycyclic arene. It consists of two benzene rings fused together, forming a bicyclic structure. Naphthalene is a white solid with a distinctive smell and is commonly used as a moth repellent. It is also a precursor for the synthesis of various compounds, including dyes, drugs, and pesticides.

Explanation:
1. Benzacephenanthrylene:
Benzacephenanthrylene is a polycyclic arene that consists of four fused benzene rings. It is a complex molecule and not the simplest example among the given options.

2. Pyrene:
Pyrene is a polycyclic arene that consists of four fused benzene rings arranged in a linear structure. It is a common component of coal tar and is known for its fluorescent properties. Pyrene is larger and more complex than naphthalene, making it a more advanced example of a polycyclic arene.

3. Dibenzanthracene:
Dibenzanthracene is a polycyclic arene that consists of three fused benzene rings. It is structurally more complex than naphthalene and is commonly used as a model compound in organic chemistry research.

4. Naphthalene:
Naphthalene is a polycyclic arene that consists of two fused benzene rings. It is the simplest example among the given options and is widely used as a starting material for the synthesis of various organic compounds.

Conclusion:
Among the given options, naphthalene is the simplest example of a polycyclic arene. It consists of two fused benzene rings and is commonly used in various applications. Understanding the structure and properties of polycyclic arenes is important for exploring their potential uses in different industries.