I do believe that it is C. crossing over :) I hope that is correct, it seems like the only plausible answer.
Hemoglobin is the protein inside red blood cells that carries oxygen. Red blood cells also remove carbon dioxide from your body, transporting it to the lungs for you to exhale. Red blood cells are made inside your bones, in the bone marrow. They typically live for about 120 days, and then they die.
Channel protein is important because it is embedded in the membrane and it also covers the membrane. This is important because the channel must transport the micromolecules and ions in and out of the cell. Carrier proteins are important because the carrier must transport the molecule in and out of the cell.
Answer:
Globally, the primary sources of greenhouse gas emissions are electricity and heat (31%), agriculture (11%), transportation (15%), forestry (6%) and manufacturing (12%). Energy production of all types accounts for 72 percent of all emissions.
