The correct option is C Producers
If CO2 is removed totally from the biosphere, producers will be affected first.
Producers are photosynthetic organisms that synthesize their own food in presence of sunlight. They convert solar energy into chemical energy. The carbon dioxide and water in the atmosphere are converted into oxygen and glucose molecule in sunlight. Hence, if carbon dioxide is removed completely from the biosphere, producers will be affected first as they cannot synthesize their food.
Thus, the correct answer is 'Producers.'