The correct answer is option 'C': Jurassic.

The Patcham Formation is a geological formation located in the southern part of England, specifically in the region of Sussex. It is an important stratigraphic unit that represents a specific time period in Earth's history. Here is a detailed explanation of why the age of the Patcham Formation is classified as Jurassic.

1. Definition of the Patcham Formation:
- The Patcham Formation is a sedimentary rock formation that consists of a sequence of various rock types, including limestone, sandstone, and siltstone. These rocks were deposited in a marine environment during a specific time in Earth's history.

2. Age of the Patcham Formation:
- The age of a rock formation can be determined by studying its fossils and comparing them to the known fossil records from different time periods. In the case of the Patcham Formation, the age has been determined to be Jurassic based on the fossils found within the formation.

3. Fossil evidence:
- Fossils found in the Patcham Formation include various marine organisms, such as ammonites, bivalves, and brachiopods. These fossils are characteristic of the Jurassic period, which occurred approximately 201 to 145 million years ago.

4. Geological context:
- The Patcham Formation is part of a larger geological sequence in the region, known as the Wealden Group. The Wealden Group consists of several formations that were deposited during different geological time periods. The Patcham Formation is located within the Lower Cretaceous portion of the Wealden Group.

5. Stratigraphic correlation:
- Stratigraphic correlation involves comparing the rock layers of different regions to establish their relative ages. By comparing the Patcham Formation to other formations in different regions, geologists have determined that it corresponds to the Jurassic period.

In conclusion, the age of the Patcham Formation is classified as Jurassic based on the fossil evidence found within the formation, its geological context within the Wealden Group, and stratigraphic correlation with other formations.