What is the auto correlation of the sequence x(n)=anu(n), 0

• A. \(\frac{1}{1-a^2}\) al (l≥0)
• B. \(\frac{1}{1-a^2}\) a-l (l<0)
• C. \(\frac{1}{1-a^2}\) a|l|(-∞<l<∞)
• D. All of the mentioned