Numbers are numbers of the form...

Answer: Third option.
Step-by-step explanation:
In order to solve the given exercise it is important to remember that:
1. Rational numbers are defined as those numbers that can be wrriten as a simple fraction.
2. The symbol for Rational numbers is: Q
3. Integers can be positive numbers, negative numbers and zero.
4. The symbol for Integers is: Z
5. Fractions have the following form:
[tex]\frac{a}{b}[/tex]
Where:
"a" is the numerator and "b" is the denominator.
The numerator "a" and the denominator "b" are both Integers ( and [tex]b\neq 0[/tex])
Therefore, based on the information given above, you can conclude that Rational numbers are numbers of the form [tex]\{\frac{a}{b}|a,b[/tex] ∈ [tex]Z,b\neq0\}[/tex]