In the common-base stage of figure below ICQ = 1 mA and

In the common-base stage of figure below I_CQ = 1 mA and β = 75. The input resistance is:

By making small-signal hybrid π-model for given fig.

r_π =	βV_T	=	75 × 26 × 10^–3	= 1.94 kΩ
	I_CQ		1 × 10^–3

v_i = I_b (r_π + 1.5 × 10³)
I_in = I_e = I_b + I_c = I_b + β I_b = (1 + β) I_b
The input resistance,

R_in =	V_in	=	I_b(r_π + 1·5 × 10³)
	I_in		(1 + β)I_b

=	1·94 × 103 + 1·5 × 10³
	1 + 75

=	3440	= 45.26 Ω
	76

Hence alternative (B) is the correct choice.