A causal system produces the output sequence y(n)={1,0.7} when excited by the input sequence x(n)={1,-0.7,0.1}, then what is the impulse response of the system function?

• A. [3(0.5)n+4(0.2)n]u(n)
• B. [4(0.5)n-3(0.2)n]u(n)
• C. [4(0.5)n+3(0.2)n]u(n)
• D. None of the mentioned