Five numbers \( x_1, x_2, x_3, x_4, x_5 \) are randomly selected from the numbers \( 1,2,3,\ldots,18 \) and are arranged in the increasing order \( (x_1 < x_2 < x_3 < x_4 < x_5) \). The probability that \( x_2 = 7 \) and \( x_4 = 11 \) is:
\( \frac{1}{136} \)
\( \frac{1}{72} \)
\( \frac{1}{68} \)
\( \frac{1}{34} \)
