The main idea of the scientists is to remove excess carbon dioxide from atmosphere.This is achieved by establishing giant seaweed farms in oceans.Later, that seaweed will be burnt for fuel. A statement can weakened the argument if it is hurting the main idea i.e if it is not able to reduce the carbon dioxide.
A. Some areas of oceanin the Southern Hemisphere do not contain sufficient nutrients to support large seaweed farms.
Incorrect. We do not care if some areas do not contain sufficient nutrients, there are many areas which can.The seaweed can still grow and reduce the co2.
B. When a seaweed plant is burned, it releases an amount of carbon dioxide comparable to the amount it has absorbed in its lifetime.
CORRECT.As it is mentioned that the sea weed will be burned for fuel, The co2 it releases will be compared to amount it absorbed , so, in all the total CO2 will not reduce and be the same.
C. Even if seaweed farms prove effective, some people will be reluctant to switch to this new fuel.
Incorrect. Beyond the scope of argument.
D. Each year about seven billion tons of carbon dioxide are released into the atmosphere but only about five billion tons are absorbed by plant life.
Incorrect.It doesn't matter how much is released, The idea is to remove excess CO2.We may think that billion ton might be big amount but the statement doesn't relate what explain what excess is ? It might be trillion ton.
E. Seaweed farms would make more money by farming seaweed to sell as nutritional supplements than by farming seaweed to sell as fuel.
Incorrect. Beyond the scope.We dont really care who does what with seaweed.