The majority of scientists believe that to reduce and stabilize atmospheric concentrations of carbon dioxide, emissions must be cut at the source by fossil fuels that are burned more efficiently and, in some cases, by alternatives such as hydrogen fuel cells that can replace fossil fuels altogether.
(A) fossil fuels that are burned more efficiently and, in some cases, by alternatives such as hydrogen fuel cells that can replace fossil fuels altogether (B) fossil fuels that are burned more efficiently and, in some cases, those that are replaced altogether with alternatives such as hydrogen fuel cells (C) burning fossil fuels more efficiently and, in some cases, by replacing fossil fuels altogether with alternatives such as hydrogen fuel cells (D) more efficiency in the burning of fossil fuels and, in some cases, by alternatives such as hydrogen fuel cells that can replace fossil fuels altogether (E) the more efficient burning of fossil fuels and, in some cases, by fossil fuels that are replaced altogether with alternatives such as hydrogen fuel cells
