Let's go through the four answer choices to see which are true or false.
A) False. A rational number like 2/3 is not a natural number (1,2,3,4,...). This is one counterexample out of infinitely many.
B) True. The set of integers is {..., -3, -2, -1, 0, 1, 2, 3, ...} basically positive and negative values that don't have fractional or decimal components. Zero is included.
C) False. Similar reasoning as choice A above.
D) False. A natural number like 7 can be written as 7/1, which means it is a rational number. Any rational number is of the form a/b with a,b being integers and b is nonzero.
