The remainder when 7$^{84}$ is divided by 342 is
$7^{84}=(7^{3})^{28}$
$\frac{ (7^{3})^{28} } {342}$ =$\frac{ (343 )^{28} } {342}$
Remainder of $\frac{ 343 } {342} =1$
As $7^{84}$ can be written as $(7^{3})^{28}$
The result will be $1^{28}$ =1
Hence Option (B)1 is the Answer.