Concept:A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.Explanation:List all prime numbers less than 50.They are: 2,3,5,7,11,13,17,19,23,29,31,37,41,43,47.Now count the numbers in this list.Counting gives: 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15.Therefore, the total number of prime numbers less than 50 is 15.Answer:Option B: 15.