a) inb) atc) ond) ofCorrect answer: at Sentence : She is good at painting. Option-by-option explanation: a) in – “Good in” is not correct in this context. It’s rarely used except for places (“good in class”). b) at – This is correct. We always use “good at” to talk about a person’s skills or abilities. Example: good at dancing, good at English. c) on – “Good on” doesn’t show ability. It’s used differently (like “good on you” meaning “well done”). d) of – “Good of” is used to express kindness (“It was good of you to help”), not skill.