The square root of which number is irrational?

Irrational numbers are numbers that cannot be expressed as a ratio of integers in the form of p/q, where p and q are integers, and q is not equal to zero. The decimal expansion of an irrational number goes on forever without repeating a pattern.

Option A: equals 4, which is a rational number because it can be expressed as .

Option B: equals 5, which is a rational number because it can be expressed as .