Ichthyology is best characterised as Science. None of the other field of studies apply to Ichthyology.
Pseudoscience are beliefs or theories that have been considered scientific. However, they are disapproved scientifically because lack of facts and evidence.
Cryptozoology is study of animals that are rumoured to exist. (Bigfoot, Loch Ness Monster, etc) It is connected with pseudoscience.
Mythology can refer to myths or the study of myths.
As you can see, the study of fish does not apply to any of the area of studies except for Science. Ichthyology applies to Science, because it is a scientific study is different aspects of various species of fish. This includes history, behaviour, and growth.
C is the most suitable answer
B is the right answer:
A more biodiverse ecosystem has a higher chance of adapting to species changes.
The evolution of sexual reproduction is a great puzzle in modern evolutionary biology. Many groups of eukaryotic organisms, especially most animals and plants, reproduce sexually. The evolution of sex between two organisms of the same species contains two related but different themes: its origin and its maintenance. However, since hypotheses for the origin of sex are difficult to test experimentally, most of the current work has focused on the maintenance of sexual reproduction. Biologists, including W. D. Hamilton, Alexei Kondrashov, and George C. Williams, have proposed various explanations for how sexual reproduction is maintained in a large set of different living things.
The answer to the question is A
