Answer:
Option (B)
Step-by-step explanation:
Properties of a rational number:
1). A decimal number which has the repeating numbers after decimal is a rational number.
Example: 2.134134134......
Here 134 is repeating after decimal so the number is a rational number.
2). A decimal number which can be written as a fraction is a rational number.
Example: 0.25 = [tex]\frac{1}{4}[/tex]
Here 0.25 can be written as a fraction [tex]\frac{1}{4}[/tex] therefore, its a rational number.
In the given options,
Option A
No repeating numbers in first number therefore its an irrational numbers.
Option B
0.684 = [tex]\frac{171}{250}[/tex]
Option C
First number is an irrational number.
Option D
First number is an irrational number.
Therefore, Option (B) is the answer.