Correct Option
The correct option is (a).
Explanation
The climatic history of North Africa indicates significant environmental transformations over geological time scales. Paleoclimatic evidence confirms that the region now known as the Sahara Desert experienced humid periods supporting extensive vegetation and animal life.
Statement-wise Analysis
- Statement 1 is Correct: Scientific evidence, including rock paintings found in the Tassili n'Ajjer region and paleoclimatic data, establishes that the Sahara was once a lush green plain. During the African Humid Period, the region supported rivers, lakes, and diverse fauna such as crocodiles, elephants, and hippopotamuses.
- Statement 2 is Incorrect: The Sahara has not always been a hot and dry region. It underwent a gradual climatic shift (desertification) caused by changes in the Earth's orbital parameters and atmospheric conditions, transforming it from a humid ecosystem into the arid desert it is today.
Key Takeaway: The Sahara Desert was historically a humid, vegetated region ("Green Sahara") before climatic changes transformed it into an arid hot desert.