Answer
We can rank the periods according to the net charge that passes through the cross section during the period:
$(a) = (b) = (c) \gt (d)$
Work Step by Step
To find the net charge, we can find the area under the current versus time graph.
(a)
$Area = 2~units$
(b)
$Area = 2~units$
(c)
$Area = 2~units$
(d)
$Area = 1~unit - 1~unit = 0$
We can rank the periods according to the net charge that passes through the cross section during the period:
$(a) = (b) = (c) \gt (d)$
