Even the most advanced neuro-diagnostic tool will sometimes fail to id

Even the most advanced neuro-diagnostic tool will sometimes fail to identify a lesion when it is present or suggest that there is one when one is not.
=> One is used as a pronoun for the noun "Lesion" in the sentence.
so there must be a symmetry of pronoun throughout the sentence.

A. a lesion when it is present or suggest that there is one (it and one - are not symmetry, also the place is not specified here to use a place pronoun)(Incorrect)

B. when a lesion is present or suggest that there is one (When depicts time, no time is specified. there is not depicting any place, so both "when and there" are creating ambiguity)(Incorrect)

C. a lesion when one is present or suggest that one is present (Symmetry of one- pronoun, no 'there' is present, clear and non-ambiguous) (Keep this)

D. when a lesion is present or suggest its presence (When depicts time, no time is specified, also its-one pronoun are not symmetrical) (Incorrect)

E. the presence of a lesion when it is there or suggest its presence (Same mistake as in D)

Answer is C