6. In virtually all types of tissue in every animal species, dioxin induces the production of enzymes that are the organism's trying to metabolize, or render harmless. the chemical that is irritating it. (A)trying to metabolize, or render harmless, the chemical that is irritating it
OG对A的解释如下:Although an "-ing" verb such as trying can sometimes be used as a noun, the phrase the organism's trying to metabolize in A is unidiomatic because trying is used as the object of organism's.