Food additives such as 3-nitro·oxy·propanol can reduce the production of this compound in one organism, which can also be reduced using red algae. Berkeley Lab’s SUMMATION project monitors the dynamics of super-producers of this compound in the San Joaquin Valley. Nickel from Permian volcanism enabled the production of this compound by a genus partly (-5[1])named “sarcina,” (15[1])which likely exacerbated the (15[1])Great Dying. (-5[3])The Mcr (15[1]-5[2])complex (-5[1])evolves (-5[1])this compound from (*) acetate (-5[1])or hydrogen (-5[1])in archaea, (10[1])which mainly generate sulfur or this compound (10[1])at “white smokers.” (10[4])Because their (10[1])environments (-5[1])are oxygen-poor, (-5[1])microbes (10[1])in rice (10[1])paddies (10[1])and wetlands are large producers of this substance, (10[4])which is also produced by (10[1])ruminant (-5[1])microbes (10[3])in (10[1])livestock. (10[6])For 10 points, (10[2])the second-most potent greenhouse (10[1])gas (10[1]-5[1])is what simplest alkane? (10[5])■END■ (10[9]0[1])