Three identical amplifiers with each one having a voltage gain of $50,$ input resistance of $1 \mathrm{~K} \Omega$ and output resistance of $250 \; \Omega$, are cascaded. The open circuit voltage gain of the combined amplifier is
- $49 \mathrm{~dB}$
- $51 \mathrm{~dB}$
- $98 \mathrm{~dB}$
- $102 \mathrm{~dB}$