A correct correspondence between pronoun and referent is...

“themselves” (line 4) - “experts” (line 3).

“they” (line 4) - “greenhouse gases” (line 4).

“those” (line 27) - “biofuels” (line 26).

“This” (line 33) - “growing soy” (line 32).

“which” (line 34) - “prices” (line 34).