burning 1 mole of O2 with hydrogen yields 572 kJ
burning 1 mole of O2 with methane yields 444 kJ
burning 1 mole of O2 with butane yields 443 kJ
burning 1 mole of O2 with octane yields 437 kJ
burning 1 mole of O2 with glucose yields 467 kJ
https://personal.utdallas.edu/~metin/Merit/MyNotes/energySci...
(-,-): antimatter would fall down, but we could break conservation laws with a mechanism.
(+,-): antimatter would fall up, but we could break conservation laws with a mechanism using electrically charged particles.
(-,+): antimatter would fall up, but ruled out by the experiment.
So what remains is (+,+)?