It is an autotroph. Think of a trough that a horse would eat of, then take the word auto. It's something that automatically feeds itself.
All options are true. However, the line "Enzymes are regulated by molecules that bind to regions other than their active site" is not 'always' true, since that line only describes non-competitive inhibition. There is another form of inhibition called competitive inhibition where an inhibitor binds directly to the active site of an enzyme, slowing the rate of reaction.
The single molecule has at least two atoms.
Energy is lost at each Trophic level of a food chain. The more levels then the more energy lost to those at the top.
