after meiosis I, the number of chromosomes is half that of a somatic cell.
The answer is A, delta.
I know this because i had this on USATestPrep and got it correct :D
Out of the choices given, the best way to describe the organisms of the Precambrian era are they were single-celled organisms and soft, boneless animals. One thing from that time that we still have today is the jellyfish. The correct answer is C.