Answer:
Phylum arthropoda includes animal which lack tissues. Arthropoda is termed as a proposed grouping of arthropods.
The answer is B- Embryological Development.
The most likely explanation for the variation is the offspring were produced from different combination of genes. A single pair of gold fish mentioned in the question means a male and a female gold fish. The two of them mated and contributed different genes to the fertilized fish eggs, this results in production of various body shape and colouration which is known as variation.
In the light reactions, H2O goes in, and O2 goes out.
