Examine the statements below and choose the correct answer:
 
1Assertion (A) - Soil erosion is the removal of top soil.

Reasoning (R) - Loss of fertile soil causes desertification.
 
2Assertion (A) - The species which are facing the risk of extinction are called endemic species.

Reasoning (R) - Natural calamities like flood and fire can cause endangerment.
 
3. Assertion (A) - Birds use sun as a guide during daytime and the stars during night.

Reasoning (R) - Birds migrate to escape the harsh cold weather.