Answer:
C
Explanation:
A natural number is a number that you would use to count kids in a class for example. Like, 1,2,3,4 and so on. 2.5 is not a natural number since there cant be 2.5 of a student. 5-151 is a negative number and there cant be negative students. -13+51=38. 38 is a natural number. Now, in D it looks like there mightve been a absolute value sign but im not sure. If D has absolute value signs then D works too. Hope I could help.