It is oxygen. Hope this helps
Answer:
It is well known that the three main sources of demographic and social statistics are censuses, surveys and administrative records. These three data sources are the principal means of collecting basic demographic and social statistics as part of an integrated programme of statistical data collection and compilation.
Explanation:
Explanation:
Reproduction in Fishes. Nearly all fish reproduce by sexual reproduction - the fusion of sperm produced from testes and eggs produced from ovaries. ... Fertilization is external in most fish species. Large quantities of eggs and sperm are simultaneously released into the water by females and males.
Answer:
The correct answer will be option-B
Explanation:
Stromatolites are the sedimentary deposited mounds made of layers of phototrophic microbes which were usually present in the primordial times. The stromatolites are one of the oldest fossils is known today which were formed in the shallow water.
They are composed of the phototrophic bacteria or cyanobacteria which survived and still survive by using the carbon dioxide and sunlight to make food material.
Since the bacteria are the prokaryotic organism therefore, the Option-B is the correct answer.
