B, overfishing in coral reef ecosystems
Answer: Are there any options? you either add C02 because it has run out gas or you and in minerals that also contain C02.
Explanation: you need C02 to have photosynthesis, so with a closed off lid, the gas is going to eventually run out.
Species that have a greater gene pool are scientifically proven to survive better than those that have a smaller gene pool. This is because the species has diversity in the genes allowing them to be able to adapt to different situations. The smaller gene pool has less diversity meaning that it cannot adapt as easily. So, the answer is most likely D. Species A will most likely go extinct and species B will continue to thrive.
18: D, homologous
20: B, DNA
I can’t see 17 or 19!