The correct option is E A
Let’s examine the sentence: “By eating too much makes a person fat.” Here, the verb ‘makes’ requires a subject and hence, ‘eating’ would be used as a gerund in this sentence. ‘Eating’ as gerund would act as a subject to the verb ‘makes’ and make clear the meaning of the sentence. So, ‘by’ would be removed as its usage treats ‘eating’ as a verb and not gerund. So, the correct way to present this sentence is, “Eating too much makes a person fat.” Hence, the part that is not be acceptable in standard written English is A. So, Option A is the correct answer.