Which of the following lines contain alliteration?

Meanwhile, his friend, through alley and street 1
Wanders and watches with eager ears, 2
Till in the silence around him he hears 3
The muster of men at the barrack door, 4
The sound of arms, and the tramp of feet, 5
And the measured tread of the grenadiers 6
Marching down to their boats on the shore. 7
Lines 1 and 2
Lines 2, 3, 4
Lines 6 and 7
Line 4 only