The correct response is: The Allies needed to maintain shipping lanes through Egypt.
North Africa, particularly Egypt, held strategic importance for the British in terms of maintaining shipping lanes. Egypt, being located in North Africa and adjacent to the Suez Canal, was a crucial link between the Mediterranean Sea and the Red Sea, providing a direct shipping route to India and other parts of Asia. Controlling Egypt allowed the British to ensure the safety and efficiency of these crucial shipping lanes, which were vital for the transportation of troops, resources, and supplies. Disrupting or capturing the Suez Canal would have severely hampered British and Allied operations in the region. Therefore, defending North Africa, specifically Egypt, was of utmost importance for the British.