Right option is (b) 444878
Explore the finest explanation: From the circuit given, IB= IB1 = 5.6µA.
IE1= IB1+ IC1 = 1.43mA + 5.6µA = 1.435mA.
IE1= IB2 = 1.435mA.
The individual current gain values,
β1=IC1/ IB1
=> β1 = 1.43mA/5.6µA= 255.36.
Similarly,β2=IC2/ IB2
=> β2 = 2.5A / 1.435mA =1742.16
Therefore, the overall current gain, β = β1 × β2 = 255.36 × 1742.16 = 444878.