It might be B) seawater.
I'm not entirely sure though, you may want to research if seawater can be created or not.
That'd be a state of quiescence called the G0 (g-zero) phase!
The role that they play is they break down dead plants and animals and waste(poop). This allows for plants to get nutrients in the means of fertilizer from what the decomposes break down. It also prevents from dead plants and animals piling up.
The doctor should check B) The amount of sodium intake the patient takes daily.
Eating salt raises the amount of sodium in your bloodstream and wrecks the delicate balance, reducing the ability of your kidneys to remove the water. The result is a higher blood pressure due to the extra fluid and extra strain on the delicate blood vessels leading to the kidneys. Adding higher blood pressure to an already hbp patient wouldn't have good results.
Hope this helps.