Final answer:
The expression 4d³ / d² is simplified to 4d.
Step-by-step explanation:
The expression 4d³/d² can be simplified by dividing 4d³ by d². When we divide two terms with the same base, we subtract the exponents. In this case, the base is d, and the exponent on the numerator term is 3, while the exponent on the denominator term is 2.
So, 4d³/d² = 4d^(3-2) = 4d.
Therefore, the expression is equivalent to 4d (option a).