Question

A.

7


B.
42


C.
84


D.
294

Answer 1

`LCD\left((9)/(14);\ (2)/(21)\right)\\\\14=2*\boxed7;\ 21=3*\boxed7\\\\therefore\\\\LCD\left((9)/(14);\ (2)/(21)\right)=\boxed7*2*3=\boxed{\boxed{42\leftarrow B}}`