Figure P3.10-4 locates the characteristic roots of nine causal, LTID systems, labeled A through I. Each system has only two roots and is described using operator notation as Q(E)y[n] = P(E)x[n]. All plots are drawn to scale, with the unit circle shown for reference. For each of the following parts, identify all the answers that are correct. Identify all systems that are unstable. Assuming all systems have P(E) = E^2, identify all systems that are real. Recall that a real system always generates a real-valued response to a real-valued input. Identify all systems that support oscillatory natural modes. Identify all systems that have at least one mode whose envelop decays at a rate of 2^-n. Identify all systems that have only one mode