Answer:
haemoglobin
Explanation:
Inside the air sacs, oxygen moves across paper-thin walls to tiny blood vessels called capillaries and into your blood. A protein called haemoglobin in the red blood cells then carries the oxygen around your body
The answer is "B. Marsupials". Marsupials undergo relatively premature births compared to many other species, and although this puts the baby at risk, it lessens the risks for the mother.
Answer: intraspecific competition
hopes this helps.
B, both chemical and biological factors are involved
Male genitalia, and the stuff that comes out of it
