Hello,
I'd say that your answer would "water". Water is the source of alot of thing's. Water help's and nourishes dirt, keeping it healthy, water keeps us from dehydrating. Water, help plant's and many other things.
Hope this helps.
~Hottwizzlers
B. Positive feedback, it decreases body temperature.
D. Fertilized egg
A zygote is a cell which is a diploid cell in the combination of the spem and egg cell. Furthermore, this cell which came from the parent cell was successfully fertilized at the fallopian tube of the female reproductive system.
A zygote will develop to become an embryo for the next few weeks.