Question : Direction: Read the following passage and answer the questions given after it.
The science of climate change is more solid and widely agreed upon than you might think. But the scope of the topic, as well as rampant disinformation, can make it hard to separate fact from fiction. Here, we've done our best to present you with not only the most accurate scientific information but also an explanation of how we know it. Climate change is often cast as a prediction made by complicated computer models. But the scientific basis for climate change is much broader, and models are actually only one part of it (and, for what it's worth, they're surprisingly accurate).

For more than a century, scientists have understood the basic physics behind why greenhouse gases like carbon dioxide cause warming. These gases make up just a small fraction of the atmosphere but exert outsized control on Earth's climate by trapping some of the planet's heat before it escapes into space. This greenhouse effect is important: It's why a planet so far from the sun has liquid water and life! However, during the Industrial Revolution, people started burning coal and other fossil fuels to power factories, smelters and steam engines, which added more greenhouse gases to the atmosphere. Ever since human activities have been heating the planet.

Question:

For what duration of time, scientists learned the green house gases?

Option 1: more than a decade
 

Option 2: more than two fortnights
 

Option 3: more than a 20 years
 

Option 4: more than a century