Every integer is also a/an[a] real number[b] rational number[c] irrational number[d] natural number.

Every integer is also a [a] real number and a [c] rational number.

An integer is a whole number, and all whole numbers are both real numbers and rational numbers. Real numbers include all numbers on the number line, and rational numbers are numbers that can be expressed as a fraction of two integers, where the denominator is not zero. Integers fit this definition as they can be written as a fraction with a denominator of 1. However, integers are not typically considered natural numbers (which are the positive counting numbers) or irrational numbers (which cannot be expressed as a fraction of two integers).