Answer:
a. Rational number
Explanation:
Whole numbers include 0 and counting numbers (1, 2, 3, etc.). This number does not fall into that category since it is a decimal that cannot be written as a whole number.
Integers include whole numbers as well as negatives of those whole numbers. Since this has a decimal, it is not an integer.
Rational numbers include any numbers that can be written as a fraction, including decimals, integers and whole numbers. Since this is a decimal, it can be written as a fraction and is a rational number.
An irrational number is a number that cannot be written as a fraction. Since this number is rational, it cannot also be irrational.