Wcompany has $3$ machines in a process. The reliability of the machines are as follows:

lachine $A-0\mathrm{.}70$

Aachine B $-0\mathrm{.}95$

Machine C $-0\mathrm{.}95$

There is one back$-$up machine for Machine A$.$ What is the reliability of the system without the back$-$up and what is the reliability of the system including the back$-$up$?($Choose closes answer$)$

Without back$-$up: $0\mathrm{.}900,$ With the back$-$up: $0\mathrm{.}953$

Without back$-$up: $0\mathrm{.}684,$ With the back$-$up: $0\mathrm{.}821$

Without back$-$up: $0\mathrm{.}632,$ With the back$-$up: $0\mathrm{.}821$

Without back$-$up: $0\mathrm{.}821,$ With the back$-$up: $0\mathrm{.}886$