The idea was that fertilizing the ocean and seas would lead to the in increase growth of phytoplankton population.
The oceanic plants do not release carbon dioxide into the air when they die because the sinks into the sea carrying with them the carbon dioxide for several centuries. This would then decrease the levels of carbon dioxide from the air as plants absorb carbon dioxide from the air during the process of photosynthesis.
C. Decreased death rate is the answer
Let's think of it like this. We have an energy crisis, but how can we solve it? There are three steps. First, we need to recognize that we HAVE a problem that needs to be fixed. Then, we need to determine what's causing the problem. Finally, we need to change how we act in order to solve the problem. Now, let's look at the options.
Is A correct, leaving our behavior unchanged? NO: if we know the cause of the problem, we still need to solve it! What about B: the problems are ignored? NO: you can't solve a problem unless you know it's a problem. C? NO: to solve a problem, you need to find out what's causing it. Finally, let's look at D: behavior is changed after cause is identified. This is correct: not only do we know why it's happening, but we're fixing it!
Answer: D
Your answer is true
Hope this helps <3