Which epoch is associated with extensive continental glaciation starting around 1.8 million years ago?

The Pleistocene Epoch is the correct answer because it is characterized by a series of glacial and interglacial periods, with extensive glaciation affecting large portions of the continents. This epoch began around 2.6 million years ago and lasted until about 11,700 years ago, during which massive ice sheets advanced and retreated across North America, Europe, and Asia. These glacial periods led to significant changes in sea levels, climate, and ecosystems, shaping the current landscape.

The other options pertain to different geological time frames and events that do not specifically highlight the feature of extensive glaciation associated with the Pleistocene Epoch. The Holocene Epoch follows the Pleistocene and marks a warmer climate with no major glaciation, while the Triassic and Jurassic are periods within the Mesozoic Era, which primarily involved different types of climate conditions and biological developments, such as the rise of dinosaurs and the evolution of early mammals. Thus, the Pleistocene is distinctly recognized for its glacial activities and is the correct choice.