The conversation with her (A) mother had a more profound (B) affect on her (C)…

“Effect” is normally a NOUN meaning a result or impact, e.g. “the effect of the medicine.” “Affect” is normally a VERB meaning to influence or change something, e.g. “the medicine did not affect her heart rate.” As a noun, “affect” has a narrow, specialized meaning: a person’s outwardly displayed emotional state or mood, e.g. “the patient had a flat affect.” So whenever a noun meaning ‘result/impact’ is needed after a determiner such as a/an/the/his/her, grammar calls for “effect,” not “affect.”

In this sentence, “a more profound affect on her” places the word right after the determiner phrase “a more profound,” in a noun slot meaning ‘impact’ — exactly the meaning that requires “effect.” So the segment marked (B), “affect on her,” contains the error; the sentence should read “…had a more profound effect on her…”

Checking every marked segment by value:

• “mother” (segment A): a common noun, correctly left lowercase (not a proper name), with the tense of “had” also correct — no error.

• “affect” (segment B): wrong part of speech/word choice here — it should be “effect” — this is the error.

• “than” (segment C): the correct comparative conjunction, correctly pairing with the earlier comparative phrase “more profound … than” — no error.

• “she expected” (segment D): correctly completes the comparison in the past tense, consistent with the rest of the sentence — no error.

• “No error”: incorrect, since the sentence does contain an error, in segment B.