Berapa sisi yang dimiliki segi delapan?

An octagon is a shape with exactly eight straight sides and eight corners, and the classic red stop sign is shaped this way specifically so drivers can recognize it by its outline alone, even from far away or when it's covered in snow.

A hexagon has six sides, and a decagon has ten, so both option two and option three describe different shapes with the wrong number of sides for a stop sign.

The prefix octo- shows up in lots of words for eight, which is also why an eight-armed sea creature is called an octopus.