Correct option is (c) 78dB
The best explanation: The total gain of ann-stage cascading amplifier is the sum of the gain measured at each stage only when the gain is calculated is decibels. Given, AV1 = 5dB, AV2 = 14dB, AV3 = 20dB, AV4 = 15dB and AV5 = 24dB
AV = AV1 + AV2 + AV3 + AV4 + AV5 = 5dB + 14dB + 20dB + 15dB + 24dB = 78dB