B is the correct answer because none of this that you put are testable.
Answer:
Free-living flatworms ingest food
Explanation:
Oxygen and Carbon Dioxide are the two gases being exchanged in the alveoli. Carbon Dioxide diffuses blood into the air, and oxygen diffuses from the air in the alveoli into the blood.
Answer:true
Explanation: cause heterozygous means that 2 or more of offspring genes are recessive