The true statement about the relationships between the number sets is:
All integers are also rational numbers.
To clarify the other options:
- Not all natural numbers are real numbers. — This is false because all natural numbers are indeed real numbers.
- Some irrational numbers are also integers. — This is false because irrational numbers cannot be integers (integers are whole numbers, and irrational numbers cannot be expressed as a ratio of two integers).
- Whole numbers include all positive and negative integers. — This is incorrect because whole numbers include only non-negative integers (0, 1, 2, ...), not negative integers.
Therefore, the only correct statement is that all integers are rational numbers.