Which statement correctly defines an Integer?

• A. A positive or negative whole number including zero.
• B. A number that can be written as a fraction.
• C. A number that has a decimal part.
• D. A number outside the real numbers.

Answer: (A)

Integers are numbers that have no fractional part; they include all whole numbers with a sign, such as negative numbers, zero, and positive numbers: ..., -2, -1, 0, 1, 2, ....

So the statement that includes "positive or negative whole number including zero" fits perfectly, since integers can be positive, negative, or zero. The other options describe different types of numbers: a fraction describes rational numbers that may not be whole; a decimal part indicates a non-integer; and a number outside the real numbers would be nonreal.