Zygotic cells duplicate and divide

According to the article Chip Off the Old Block which discussed genetics and the Colorado Adoption Project, the SES of the biological parents placing their children up for adoption was lower than the adoptive parents because:

(a) these biological parents were from poor families and had, themselves, been raised on welfare (b) their newborns had cost so much money already that they were financially depleted (c) child support payments had not yet started to the adoptive mothers (d) biological parents were largely young people

Iconic and echoic memories are part of the stage of memory known as memory

Fill in the blank with correct word