( )all behavior is learned behavior is a badic assumption of social scientists.
A) nearly
B) that nearly

답은b인데, 왜 굳이 that 이필요한지 이해가 잘 안됩니다ㅠ

( )map dates back to about 3,000B.C.
A) known to be the oldest
B) It was the oldest known
C) Known as the oldest
D) the oldest known
답은 d인데 다른건 왜 안되는지 잘모르겠어요

부탁드립니다ㅠ