1)

$\frac{3}{4}\left(1+\frac{1}{3}\right)\left(1+\frac{2}{3}\right)\left(1- \frac{2}{5}\right)\left(1+\frac{6}{7}\right)\left(1-\frac{12}{3}\right)=$ ?

A) $\frac{1}{5}$

B) $\frac{1}{6}$

C) $\frac{1}{7}$

D) None of these

Given = $\left( \frac{3}{4}\times\frac{4}{3}\times \frac{5}{3}\times \frac{3}{5}\times \frac{13}{7}\times \frac{1}{13}\right)=\frac{1}{7}$