Question

Compared to other animals, humans spend a lot of time and energy controlling and changing their environments. During the Stone Age, humans started using fire for cooking and staying warm. They invented tools for hunting, fishing, farming, and building. From that time, human advances have continued at an amazing rate. Each advance seems to lead to many more.

For a long time, scientists believed that only humans could make and use tools. They said only humans could use reasoning and planning to solve problems. However, recent animal research shows that these ideas are mistaken. As it turns out, the animal world is full of tool users and problem solvers.

Researchers have studied many of these animals by observing them in the wild or by setting up problem-solving experiments. In 1960, scientist Jane Goodall began observing chimpanzees in Tanzania, Africa. She noticed how chimps used two different sticks to get the termites they ate from their mounds in the ground. First, a chimp would use a strong, heavy stick to poke a hole into the mound. Next, the chimp would find a slender, leafy stick, pull off its leaves, and push it into the hole. Then the chimp would pull the stick back out and eat the termites that clung to it.

Goodall's work led researchers to observe other members of the ape family, including gorillas and orangutans. These animals also demonstrated tool use and problem solving. Some people linked apes' abilities to the fact that they have large brains and human-like hands. But more research has disproved this explanation. For example, in 2009, scientists experimented with birds called rooks. The scientists presented a rook with some pebbles and a tube of water with a worm floating in it. The water was too low for the rook to reach in with its head to get the worm. But by picking up pebbles in its beak and dropping them into the tube, the rook raised the water level enough to reach the worm. The study showed that an animal without hands or an ape-like brain could also use tools to solve a problem.

There are other examples of animals solving problems with tools. They include otters that pound shellfish to open rocks and elephants that scratch themselves with sticks. Of course, these tools are simple objects that animals find nearby. Animals' tools are quite different from hammers, saws, scissors, and other tools made by humans.

Which sentence from the passage BEST supports the idea that the animal world is "full of tool users and problem solvers"?

a
"Researchers have studied these animals by observing them in the wild or by setting up problem-solving experiments."
b
"They include otters that pound shellfish to open rocks and elephants that scratch themselves with sticks."
c
"Goodall's work led researchers to observe other members of the ape family, including gorillas and orangutans."
d
"Compared to other animals, humans spend a lot of time and energy controlling and changing their environments."

Answer 1

b

This sentence gives concrete examples of different animal species using tools, which directly supports the claim that many animals are tool users and problem solvers.