3.13113111311113… is :

Correct option is B

Given:

Number = 3.13113111311113…

Concept used:
A number is rational if its decimal expansion is either terminating or repeating (recurring).
If it is non-terminating and non-repeating, it is irrational.

Solution:
Here, the digits after the decimal are:
13, 113, 1113, 11113, …

The number of 1’s before 3 keeps increasing, so the pattern never repeats.
Hence, the decimal is non-terminating and non-repeating.

Correct answer is (b) an irrational number.