The correct option is A 16 : 1
Current is given by i=neAvd, where
n = no. of electrons,
e = electron charge,
A = cross-sectional area of the conductor and
vd = drift velocity of electrons.
Since, n and e are constant:
i1i2=A1A2×vd1vd2,
⇒i1i2=r21r22×vd1vd2
⟹41=1222×vd1vd2
⟹vd1vd2=4×41×1=16:1.