To simplify the expression \((1/3)^6 \times (1/3)^3\) using the product rule of exponents, you add the exponents together. The product rule states that:
\[ a^m \times a^n = a^{m+n} \]
In this case:
\[ (1/3)^6 \times (1/3)^3 = (1/3)^{6+3} = (1/3)^9 \]
Therefore, the equivalent form is:
a) \((1/3)^{9}\).