Zero belongs to the following sets of real numbers:
- Whole numbers (0, 1, 2, 3, ...)
- Integers (..., -2, -1, 0, 1, 2, ...)
- Rational numbers (any number that can be expressed as a fraction, which includes 0 since it can be expressed as 0/1)
Therefore, the correct choice is:
d. whole numbers, integers, and rational.