Which of the following is widely regarded in classical geography as the highest active volcano in the world?

Introduction / Context:
Volcanoes are often compared based on height, location and activity. Many school and competitive exam books refer to a particular volcano in the Andes of South America as the highest active volcano in the world, based on classical geographical knowledge. This question tests whether you can recall that name from the list of famous volcanoes provided in the options.

Given Data / Assumptions:

• Four well known mountains are listed: Mount Etna, Mount Fuji, Mount Tai and Cotopaxi.
• The question asks about the highest active volcano according to classical geography sources.
• We assume the commonly used facts in standard exam oriented material rather than revised scientific records for this specific question.

Concept / Approach:
Cotopaxi is a prominent volcano located in the Andes range in Ecuador. It is one of the highest active volcanoes in the world and has been active multiple times in recorded history. Older geography texts often describe Cotopaxi as the highest active volcano, even though modern measurements may identify slightly higher active peaks. Mount Etna in Italy and Mount Fuji in Japan are famous but not as high as Cotopaxi. Mount Tai in China is important culturally but is not primarily known as a high active volcano. Therefore the approach is to match the description highest active volcano in classical exam references with Cotopaxi.

Step-by-Step Solution:
Step 1: Recall that Cotopaxi lies in the Andes, a very high mountain chain in South America with many volcanic peaks.Step 2: Understand that Cotopaxi has an elevation of more than five thousand metres and is known for eruptions, which qualifies it as an active volcano.Step 3: Compare it with Mount Etna, which is active but lower in height and situated in Sicily, and with Mount Fuji, a volcanic cone in Japan that is also lower than Cotopaxi.Step 4: Recognise that Mount Tai in China is a sacred mountain but is not described in standard texts as the highest active volcano.Step 5: Conclude that in classical geography questions, Cotopaxi is treated as the highest active volcano in the world.

Verification / Alternative check:
Older school level references and many competitive exam guides list Cotopaxi specifically under the heading highest active volcano. While modern research may update these rankings as measurements change, exam questions usually follow these traditional statements. Cross checking with such material shows that Cotopaxi is consistently identified for this fact, whereas Mount Etna, Mount Fuji and Mount Tai are associated with other geographical distinctions.

Why Other Options Are Wrong:
Mount Etna: An active volcano in Sicily, Italy, but its height is significantly lower than that of Cotopaxi.Mount Fuji: A famous cone shaped volcano in Japan, but again not as high as Cotopaxi and often considered dormant in some classifications.Mount Tai: An important mountain in China, celebrated for cultural and religious reasons, not as the world highest active volcano.

Common Pitfalls:
Students may be tempted by Mount Etna or Mount Fuji because these volcanoes are very famous and frequently mentioned in textbooks and media. Another source of confusion is the difference between scientifically updated lists and the more stable facts used in competitive exams. When answering such questions, it is important to stay aligned with the traditional facts typically taught in standard geography courses, which clearly associate the label highest active volcano with Cotopaxi.

Final Answer:
The volcano widely regarded in classical geography as the highest active volcano in the world is Cotopaxi.