Scientists are working on a new project to clean plastic waste from the oceans. They have developed a special robot that can collect plastic pieces. The robot uses solar energy and can work for hours. This invention may help reduce pollution in the seas.
Which of the following questions does **NOT** have an answer in the text?
A)What is the robot's energy source?
B)How long can the robot work?
C)Who invented the robot?
D)What is the purpose of the robot?