Concept:A prime number is a natural number greater than 1 that has exactly two distinct positive divisors: 1 and itself.Explanation:To find the total number of prime numbers up to 100, we list all primes from 2 to 97.The prime numbers up to 100 are:2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97.Counting these values gives a total of 25 primes.Thus, the number of prime numbers up to 100 is 25.Answer:Option A, 25.