IMO A.
A. dioxide, accounts for 11 percent of all domestic greenhouse gas emissions,:Correct. noun+noun modifier correctly modifying all domestic green house gas emissions.
B. dioxide, accounts for 11 percent of all domestic greenhouse gas emissions;:The second part marks the beginning of independent clause with "that" referring to the subject of the first independent clause that is methane. Incorrect.
C. dioxide and accounts for 11 percent of all domestic greenhouse gas emissions;
...
A. dioxide, accounts for 11 percent of all domestic greenhouse gas emissions,:Correct. noun+noun modifier correctly modifying all domestic green house gas emissions.
B. dioxide, accounts for 11 percent of all domestic greenhouse gas emissions;:The second part marks the beginning of independent clause with "that" referring to the subject of the first independent clause that is methane. Incorrect.
C. dioxide and accounts for 11 percent of all domestic greenhouse gas emissions;
...




