Which of the following system is causal?$

• A. y[n] = 2[n] ‚Äö√Ñ√∂‚àö√ë‚àö¬® 3[n+1]
• B. y[n] = 2[n] + 3
• C. y[n] = 2[n-7] ‚Äö√Ñ√∂‚àö√ë‚àö¬® 3[n+1]
• D. y[n] = 2[n]*3[n+1]