Answer:
In heart valve disease, one or more of the valves in your heart doesn't work properly. Your heart has four valves that keep blood flowing in the correct direction. In some cases, one or more of the valves don't open or close properly. This can cause the blood flow through your heart to your body to be disrupted.
Dead things were once living, such as a dead plant. Non-living things were never alive, like coal.
Hydrocarbons is the simplest organic compound mad by hydrogen and carbon
I think the correct answer from the choices listed above is option B. The difference in biodiversity between the tundra and the tropical rain forest would be that warmer temperatures and higher average rainfall in the tropical rainforest allow more things to survive. Hope this answers the question.