Which number among the options is NOT considered a rational number?

The correct choice is π, as it is not considered a rational number. Rational numbers are defined as numbers that can be expressed as the quotient of two integers, where the denominator is not zero. For example, the numbers 3, 22/7, and -1/3 can all be represented in this form. The number 3 can be expressed as 3/1, 22/7 is already in the form of a fraction, and -1/3 is also a fraction where both the numerator and denominator are integers.

On the other hand, π (pi) is an irrational number, which means it cannot be expressed as a fraction of integers. The decimal representation of π is non-repeating and non-terminating (approximately 3.14159...), which further confirms its irrational nature. Thus, π stands out among the options as the only number that does not fit the definition of a rational number.