The word "impeccable" in this sentence means faultless or perfect, so the word that is most nearly the same in meaning is option D, "faultless."

When we say someone has an "impeccable" style, it means their style is flawless or without fault. So, in this sentence, "impeccable" is used to describe the high quality and precision of the person's style. Option A, "inoffensive," doesn't fit because it means something that does not cause offense or harm, which is not the same as being faultless or perfect. Option B, "upright," means honest and honorable, but it does not fit the context of describing someone's style. Option C, "harmless," means not likely to cause harm or injury, which also does not relate to the meaning of "impeccable."