The Rapa Nui civilization is famous for constructing massive *moai*, or human-shaped statues averaging 13 feet tall, on the island now known as Easter Island. The history and fate of the civilization has long been a subject of discussion for archaeologists.
The people first arrived on the island around 1,200 years ago on wooden canoes and subsisted on fishing, hunting, and agriculture on the island. Although the soil on the island was not naturally nutrient-rich, the settlers found that it was suitable for staples such as sweet potatoes, and the waters surrounding the island had plentiful fish that the people were skilled at catching. At its peak, it is believed that the Rapa Nui society on the island reached a population of 10,000 to 20,000 people spread throughout many chiefdoms.
At the time of the Rapa Nui arrival, the 63-square mile volcanic island was covered in palm trees. To carry the massive blocks of rock needed for the moai, to construct canoes for fishing, to build fires, and to clear land for agriculture, the people cut down the native palm trees.
The deforestation increased soil erosion, which wiped out the habitat for the island’s native bird and animal species. As the supply of trees dwindled on the island, the people lost their means to fish, hunt, build homes, and construct fires. Scientists have long believed that the loss of the trees on the island ultimately led to the downfall of the once‑thriving society.
Select the practices that contributed to the Rapa Nui society's lack of sustainability.
a. significantly increased their population after settling on the island
b. planted crops that were not native to the island
c. adjusted dietary habits to suit local ecosystem
d. devoted labor and nonrenewable volcanic rock to construct moai
e. exhausted energy sources provided by the local ecosystem