∧m0 for NaCl, HCl and NaA are 126.4, 425.9 and 100.5 S cm2 mol–1, respectively. If the conductivity of 0.001 M HA is 5 × 10⁻¹ S cm⁻⁵, degree of dissociation of HA is :
(1) 0.125
(2) 0.75
(3) 0.50
(4) 0.25