Which area in Manila was built by the Americans to serve as oil depots?

The area in Manila built by the Americans to serve as oil depots is Pandacan. During the American colonial period, particularly in the early 20th century, Pandacan emerged as a significant site for the storage and distribution of oil products. The strategic location near the Pasig River made it ideal for shipping and logistics, facilitating efficient transportation of petroleum resources.

This development was part of broader urban planning and industrialization efforts initiated by American authorities in Manila to modernize the city and support growing economic activities, especially in the energy sector. The presence of oil depots in Pandacan also contributed to the area's industrial landscape, as it became a hub for fuel and related services during that time.

Other areas listed—Malate, Sta. Cruz, and Sampaloc—did not play the same significant role in the establishment of oil depots. While these neighborhoods have their importance in Manila's history and development, they were not specifically designated for oil storage and distribution by the American administration, making Pandacan the correct answer.