Answer:
C. 6*9^3 + 1*9^2 + 1*9^1 + 5*9^0
Explanation:
In base 9, each digit to the left represents a power of 9.
The rightmost digit represents 9^0, the next digit to the left represents 9^1, the next digit to the left represents 9^2, and the 4th digit represents 9^3.
Answer: C. 6*9^3 + 1*9^2 + 1*9^1 + 5*9^0