Diagonals in a Regular Polygon

In a regular polygon with n sides, the number of diagonals can be calculated using the formula:

$$ D = \frac{n(n-3)}{2} $$

Consider a polygon where the number of sides, n, is a prime number greater than 5. Determine whether the quantity of diagonals, Quantity A, is greater than, less than, or equal to the number of sides, Quantity B. Which of the following statements is true?