To determine the measure of \(\overline{AC}\), we first note that \( \overline{AB} \) is given as 22.3 millimeters. Nozomi constructed a copy of \(\overline{AB}\), which means that \(\overline{AC}\) is actually twice the length of \(\overline{AB}\), since point \(B\) is the endpoint of the copy.
Therefore, the calculation for \( \overline{AC} \) is:
\[
\overline{AC} = \overline{AB} + \overline{AB} = 22.3 \, \text{mm} + 22.3 \, \text{mm} = 44.6 \, \text{mm}
\]
Based on the options provided, the correct response would be:
**The measure of \(\overline{AC}\) is 44.6 millimeters.**