\( \begin{array}{lll} & & 3,458.9 \div \square \\ \text { A. } 10^{1} \\ \text { B. } 10^{2} \\ \text { C. } 10^{3} \\ \text { D. } 10^{4}\end{array} \)

\[ \text{Step 1: Identify the problem.} \] We have the number \(3,458.9\) and we want to choose a power of 10 from the options \(10^1,\,10^2,\,10^3,\,10^4\) such that dividing \(3,458.9\) by that power of 10 gives a result in the range from 1 (inclusive) to 10 (exclusive). This format is characteristic of scientific notation. \[ \text{Step 2: Write } 3,458.9 \text{ in scientific notation.} \] To do that, we want to express \(3,458.9\) as \(a \times 10^n\) where \(1 \leq a < 10\). Observe that: \[ 3,458.9 = 3.4589 \times 10^3. \] \[ \text{Step 3: Interpret the division.} \] Since \[ \frac{3,458.9}{10^3} = 3.4589, \] dividing by \(10^3\) converts the original number into its scientific notation form (with the coefficient \(a = 3.4589\) in the proper range). \[ \text{Step 4: Choose the correct option.} \] Among the given options, the power of 10 that works is \(10^3\). Thus, the answer is: \[ \boxed{10^3} \]