Final answer:
The radical 81d^6 simplifies to 9d^3 by taking the square root of both the number and the variable terms independently.
Step-by-step explanation:
We have been asked to simplify the radical 81d^6. Starting with the number 81, we know that the square root of 81 is 9 because 9 times 9 equals 81. As for the variable term d^6, we can simplify this by taking the square root of d^6, which gives us d to the power of 3 (since squaring d^3 results in d^6).
Therefore, the simplified form of the radical 81d^6 is expressed as 9d^3, which matches option A).