An improper fraction is a fraction where the numerator is greater than or equal to the denominator. Let's analyze the options:
A. \( \frac{20}{25} \) - Proper fraction (20 < 25) B. \( \frac{25}{20} \) - Improper fraction (25 > 20) C. \( 7 \frac{2}{9} \) - Mixed number (whole number with a proper fraction part) D. \( 2 \frac{9}{7} \) - Mixed number with an improper fraction part, but overall still a mixed number.
The only improper fraction listed is B. \( \frac{25}{20} \).