Two discrete time systems with impulse responses h1[n] =`delta`[n - 1] and h2[n] = `delta`[n -2] are connected in cascade. The overall impulse response of the cascaded system is
`delta`[n - 1] + `delta`[n - 2]
`delta`[n - 4]
`delta`[n -3]
`delta`[n -1] `delta`[n -2]