Q) 다음글에서 전체 흐름과 관계 없는 문장은?
Picture writing was probably originated by people who lived centuries ago in a time

that is called the Stone Age.1)It has also been employed by many people since then.

2) Some Native Americans, for example, were still using this method of

communicating when that country was being settled. 3) Even today we still use

symbols. 4) Ancient Egyptians took the next step in the improvement of written

language and developed written symbols called hieroglyphics. 5) One is figure S

that warns of a double curve; another is an arrow to point out the right direction; and

a third is a skull and crossbones to signify poison.
정답은 4번이네요. 전 3번을 답이라고 했는데,,,

설명좀 부탁드립니다.