Is an organism in its earliest stage of development. In humans, this is the stuff and defined as the developing organism from the fourth day after fertilization to end of the week. After that unborn baby is usually referred to as the fetus.
Answer:
What do you need to be answered
Explanation:
Because a<span>t some point during its life cycle, it had a dorsal hollow nerve chord, notochord, pharyngeal gill slits, and finally a muscular tail.
hope this helped and is right :)</span>
The answer would be (levels) goodluck
