All scholars have the habit of staying up late, and Zhang Mu often stays up late, so Zhang Mu must be a scholar. Which of the following fully reveals the errors of the above form of reasoning? ['All smart people are nearsighted, Jiang Lang is very nearsighted, so Jiang Lang is very smart.', 'All pigs have four legs, but this animal has eight legs, so it is not a pig.', 'All prime numbers are natural numbers, 91 is a natural number, so 91 is a prime number.', "I'm a fool because all smart people are nearsighted and my vision is quite good."]