Answer:
C)
Step-by-step explanation:
We have to find the property which would be useful in proving that the product of two rational numbers is always rational.
Rational number: It is that number which can be expressed as where p and q are both integers,
We know that product of two rational numbers is always a rational number.
Let and are twp rational numbers.
Product of these two rational numbers is given by
a, b, c and d are integers and
Product of two integers is always an integer.
Therefore, ac and bd are integers and
Hence, we can say that product of two rational numbers is always a rational number.
Option C is true.