Which sentence states the central idea of the passage? You might be surprised to learn that robots have existed for hundreds
of years. Long before the development of modern electronics,
inventors were creating human- or animal-shaped robotic contraptions.
These robots used springs, levers, weights, and clockworks to do
simple tasks. Some of the most famous include a robotic knight
designed by Leonardo da Vinci in 1495 and an artificial duck from
1739 that could swim, flap its wings, and even eat and digest grain.
A. Robots have been around for a long time, but the advances made
in the 21st century are much more significant than those made
earlier