I believe 3 is the answer, because I think the U.S bought a part of Mexico.
The correct answer is:
Musa’s spending resulted in gold becoming less valuable in Cairo.
Musa unwittingly destroyed the economies of the cities of Cairo, Medina, and Mecca. The unforeseen influx of gold decreased the metal´s value for a decade resulting in hugely inflated prices.
To amend the gold market, Musa obtained all the gold he could carry on his way back from Mecca at high interest, becoming the only man recorded in history who controlled the price of gold in the Mediterranean.
