Given that S1 and S2 are two discrete time systems. Consider the following statements:i) If S1 and S2 are linear, then S is linearii) If S1 and S2 are non-linear, then S is non-lineariii) If S1 and S2 are causal, then S is causaliv) If S1 and S2 are time invariant, then S is time invariantThe true statements from the above are ____________

• A. i, ii, iii
• B. ii, iii, iv
• C. I, iii, iv
• D. I, ii, iii, iv