Explanation:

To determine if a pair of fractions is equivalent, we need to check if they represent the same value or not. This can be done by simplifying both fractions and comparing their simplified forms.

Let's simplify each option to determine which one is equivalent.

a) 7/8, 56/72:
To simplify 7/8, we can divide both the numerator and denominator by their greatest common divisor (GCD), which is 1. So, 7/8 is already in its simplest form.
To simplify 56/72, we can divide both the numerator and denominator by their GCD, which is 8. So, 56/72 simplifies to 7/9.
Since 7/8 and 7/9 are not equal, option a) does not have a pair of equivalent fractions.

b) 12/25, 48/100:
To simplify 12/25, we can divide both the numerator and denominator by their GCD, which is 1. So, 12/25 is already in its simplest form.
To simplify 48/100, we can divide both the numerator and denominator by their GCD, which is 4. So, 48/100 simplifies to 12/25.
Since 12/25 and 12/25 are equal, option b) has a pair of equivalent fractions.

c) 9/14, 45/76:
To simplify 9/14, we can divide both the numerator and denominator by their GCD, which is 1. So, 9/14 is already in its simplest form.
To simplify 45/76, we can divide both the numerator and denominator by their GCD, which is 1. So, 45/76 is already in its simplest form.
Since 9/14 and 45/76 are not equal, option c) does not have a pair of equivalent fractions.

d) 11/14, 55/76:
To simplify 11/14, we can divide both the numerator and denominator by their GCD, which is 1. So, 11/14 is already in its simplest form.
To simplify 55/76, we can divide both the numerator and denominator by their GCD, which is 1. So, 55/76 is already in its simplest form.
Since 11/14 and 55/76 are not equal, option d) does not have a pair of equivalent fractions.

Conclusion:
Among the given options, only option b) has a pair of equivalent fractions, which are 12/25 and 48/100.