The build up of lactic acid will need oxygen to break it up. Lactic acid is why muscles feel tired after excess exercise
The correct option is D.
A virus refers to an infectious micro organism that is made up of nucleic acid molecule that is enclosed within a protein coat. Viruses are only able to reproduce and multiply when they come in contact with living cells, in the absence of living cells they remain dormant and they do not show any sign of been a living thing. The nuclei acid molecule of a virus can be in form of a DNA molecule or a RNA molecule.
I believe true because the Precambrian is the first geologic time, going back 4600-570 years ago, meaning it should contain the earliest of things.