Directions: Read the Assertion (A) and Reason (R) carefully and choose the correct alternative. Assertion (A): An increase in the concentration of carbon dioxide in the atmosphere would lead to melting of polar ice. Reason (R): A higher concentration of carbon dioxide causes an increase in global average temperature.

Introduction / Context:
This question is about climate change and the greenhouse effect. It asks whether rising carbon dioxide levels in the atmosphere can cause melting of polar ice and whether the given Reason about increasing global temperature provides the correct explanation. Understanding this link is important for general awareness about environmental issues and is frequently tested in school science and competitive exams.

Given Data / Assumptions:

• Assertion (A) states that an increase in carbon dioxide would melt polar ice.
• Reason (R) states that global temperature would rise as carbon dioxide concentration increases.
• Carbon dioxide is a major greenhouse gas.
• Polar ice refers to ice caps and glaciers in polar regions such as Antarctica and the Arctic, and high mountain glaciers.

Concept / Approach:
The greenhouse effect is a natural process where certain gases in the atmosphere trap heat radiated from the Earth s surface and keep the planet warm enough for life. Increasing levels of greenhouse gases, especially carbon dioxide, intensify this effect and raise global average temperature. Higher temperatures can lead to melting of ice in polar and glacial regions. Therefore, to evaluate this Assertion and Reason pair, we must connect greenhouse gas concentration, temperature rise, and ice melt.

Step-by-Step Solution:
Step 1: When carbon dioxide concentration in the atmosphere increases due to human activities such as burning fossil fuels and deforestation, the greenhouse effect becomes stronger. Step 2: A stronger greenhouse effect means more heat is trapped in the lower atmosphere, leading to an increase in the global average temperature. This supports Reason (R) and shows that it is true. Step 3: Higher global temperatures particularly affect cold regions. Polar ice caps and mountain glaciers are sensitive to small temperature changes. Step 4: As average temperatures rise, more ice melts during warm seasons and less ice forms during cold seasons. Over time, this leads to a net reduction in ice volume. Step 5: Therefore Assertion (A) is also true because increased carbon dioxide indirectly leads to melting of polar ice through the mechanism of global warming. Step 6: Reason (R) directly describes the first link in the chain, that is, carbon dioxide increase causes temperature rise, which in turn explains the effect on polar ice stated in the Assertion.

Verification / Alternative check:
Scientific reports, including those by international climate panels, show observed trends of rising atmospheric carbon dioxide, increasing global average temperatures, and significant retreat of many glaciers and polar ice regions. Satellite images and long term measurements confirm loss of ice in Greenland, Antarctica, and many mountain ranges. These independent lines of evidence support both the Assertion and the Reason and confirm that the Reason explains the Assertion.

Why Other Options Are Wrong:
Options that deny the truth of either the Assertion or the Reason conflict with widely accepted climate science. Saying that Reason (R) does not explain Assertion (A) ignores the clear cause and effect link between greenhouse gas driven warming and ice melt. Therefore such options cannot be correct.

Common Pitfalls:
Some learners may think that melting of polar ice is caused directly by pollution particles or chemical reactions rather than by temperature rise. Others may confuse local weather variability with long term climate trends. It is essential to distinguish between short term weather changes and long term climate change driven by greenhouse gases.

Final Answer:
Both Assertion (A) and Reason (R) are true, and Reason (R) correctly explains Assertion (A), so the correct option is Both Assertion (A) and Reason (R) are true, and Reason (R) correctly explains Assertion (A).