Answer:
The earliest oxygen-producing life forms were Cyanobacteria. Besides Cyanobacteria, these tiny organisms have another name known as blue-green algae
Explanation:Some scientists think that 2.4 billion years ago is when organisms called cyanobacteria first evolved, which could perform oxygen-producing (oxygenic) photosynthesis. Other scientist think that cyanobacteria evolved long before 2.4 billion years ago but something prevented oxygen from accumulating in the air
Answer:
Insulin and glucagon
Explanation:
Insulin and glucagon are hormones that help regulate the levels of blood glucose, or sugar, in your body.
Answer:
at least 1,000 people per square mile
Explanation:
I took the test it was correct. ( i know thats not an explanation im sorry but its correct).
I would guess C, hope that helps!
