The correct option is A a
Let’s examine the sentence: “Never I asked my Englishman how much he earned.” The sentence states an action that happened and completed in the past. So, the sentence should be in past perfect tense. Past perfect tense indicates that an action was completed (finished or "perfected") at some point in the past before something else happened. This tense is formed with the past tense form of "to have," i.e. had, plus the past participle of the verb. So the verb “asked,” which is the past participle of “ask” should be preceded by “had.” The correct sentence would be, “Never had I asked my Englishman how much he earned.” So, the error is in Part a of the sentence. Hence, Option A is the correct answer.