Answer:d
Explanation:
Drift velocity is given by
[tex]v_d=\frac{I}{n\times Q\times A}[/tex]
where [tex]v_d[/tex]=drift velocity
I=Current
n=no of electron
Q=charge of Electron
A=cross-section
If area of cross-section decreases gradually then drift velocity will increase because drift velocity is inversely proportional to Area of cross-section