Final answer:
The final borders of British Mandate Palestine were significantly influenced by the British need to secure access to oil and to maintain stable relations with both Jewish and Arab populations, which led to the irregular and contested borders that resulted in ongoing conflict.
Step-by-step explanation:
One of the most significant factors influencing the final borders of British Mandate Palestine was the British desire to secure access to oil and maintain good relations to protect their interests in the Middle East. The British had previously issued the Balfour Declaration, which expressed support for a Jewish homeland in Palestine, while simultaneously promising support for Arab nationalism during World War I. The complicated promises made to both Jewish and Arab populations, the strategic importance of Middle Eastern oil reserves, and the desire to avoid jeopardizing relations with local Arab leaders contributed to the complex and contentious delineation of borders in the region.
Following World War II, the British found themselves unable to solve the Zionist-Arab conflict and passed the responsibility to the United Nations. The UN's partition plan created separate Jewish and Arab states, but neither population was satisfied, and the immediate outcome was a war that led Israel to extend its borders beyond the UN partition lines. This reshaping of borders resulted in the displacement of hundreds of thousands of Arab Palestinians, fueling a conflict that continues to have ramifications today.