Which statement about irrational numbers is correct?

Irrational numbers are defined as numbers that cannot be expressed as a simple fraction, meaning they cannot be represented as a ratio of two integers. A crucial characteristic of irrational numbers is that when they are expressed in decimal form, their decimal expansions are non-terminating and non-repeating. This means that they continue infinitely without any repeating pattern. For example, numbers like √2 or π are irrational because their decimal forms continue without repetition, like 1.41421356... for √2 and 3.14159265... for π. This characteristic sets irrational numbers apart from rational numbers, which can be expressed as either terminating or repeating decimals.

The other options do not accurately reflect the properties of irrational numbers. While rational numbers can be expressed as fractions or have finite decimal representations, irrational numbers specifically do not fit those definitions. Thus, the statement that highlights the unique and defining property of irrational numbers is the one indicating that they can be represented as a decimal that continues indefinitely without repeating.