حاصل عبارت $\frac{\frac{1}{2}-\frac{1}{3}}{\frac{1}{3}-\frac{1}{4}}\times \frac{\frac{1}{4}-\frac{1}{5}}{\frac{1}{5}-\frac{1}{6}}\times \frac{\frac{1}{6}-\frac{1}{7}}{\frac{1}{7}-\frac{1}{8}}\times ....\times \frac{\frac{1}{48}-\frac{1}{49}}{\frac{1}{49}-\frac{1}{50}}$ کدام است؟
1 )
$\frac{1}{50}$
25
3 )
$\frac{1}{35}$
4 )
50