Let's break down each statement to see which one is true:
A. **Whole numbers include all natural numbers and 0.**
- This statement is **true**. Whole numbers are defined as the set of natural numbers (1, 2, 3,...) along with 0 (0, 1, 2, 3,...).
B. **Some irrational numbers are also integers.**
- This statement is **false**. By definition, irrational numbers cannot be expressed as a fraction of two integers, and integers are whole numbers without fractions or decimals.
C. **Not all natural numbers are real numbers.**
- This statement is **false**. All natural numbers are indeed real numbers; natural numbers are a subset of real numbers.
D. **All rational numbers are also integers.**
- This statement is **false**. While all integers are rational (as they can be expressed as a fraction with a denominator of 1), not all rational numbers are integers. For example, 1/2 is a rational number but not an integer.
Thus, the only true statement is **: Whole numbers include all natural numbers and 0.