I'd go with option D. Though we cannot see exactly what has changed, as changes are often quite gradual, we can observe intermediates that link different species together.
Carbon-14 is a form of Absolute Dating
The correct answer is D. Flask 3 (only). This is because fish produce carbon dioxide products of cellular respiration and they do not undergo photosynthesis therefore not consuming carbon dioxide.
This is where cellular respiration is being involved.
Cellular respiration is termed as process and reaction of metabolic which takes place in organisms where biochemical energy are converted to adenosine triphosphate from nutrients where waste product is being released.
Catabolic reactions is involved in cellular respiration where large molecules are broken to small molecules so as to release energy.