Option 1: This option suggests that the Sahel region is the core area of the Sahara desert. However, this is not correct. The Sahel region is actually located at the southern moving edge of the Sahara desert, rather than being the core area of the desert.

Option 2: This option correctly states that the Sahel region is associated with the southern moving edge of the Sahara desert. The Sahel is a transitional zone between the desert and the savanna grasslands. It experiences a semi-arid climate with limited rainfall and is known for its drought-prone conditions.

Option 3: This option suggests that the Sahel region is the northern fringe of the Sahara desert, bordering the Mediterranean Sea. However, this is not accurate. The Sahel region is located further south, away from the Mediterranean Sea.

Option 4: This option states that Sahel is another name for the Sahara desert. However, this is incorrect. Sahel and Sahara are two distinct regions. The Sahara desert is the large desert located across North Africa, while the Sahel is the transitional zone south of the Sahara.

In conclusion, the correct answer is option 2, which states that the Sahel region is associated with the southern moving edge of the Sahara desert.