If the sum of the series \( \frac{1}{1 \cdot (1 + d)} + \frac{1}{(1 + d)(1 + 2d)} + \ldots + \frac{1}{(1 + 9d)(1 + 10d)} \) is equal to \( 5 \), then \( 50d \) is equal to:
\( 10 \)
\( 15 \)
\( 5 \)
\( 20 \)