Let Ajay's age at the time of his marriage be $x$ years.
Since Ajay got married 9 years ago, his present age is:
$x + 9$
According to the given condition:
$\text{Present age} = \frac{13}{4} \times \text{Age at the time of marriage}$
$x + 9 = \frac{13}{4} x$
Multiply both sides by 4 to eliminate the fraction:
$4(x + 9) = 13x$
$4x + 36 = 13x$
Rearrange the equation:
$36 = 13x - 4x$
$36 = 9x$
Solve for $x$:
$x = \frac{36}{9} = 4$
Ajay's present age is:
$4 + 9 = 36$ years.
Thus, the correct answer is **D) 36 years**.