To determine which situation results in a change that could be modeled by a positive number, we need to focus on the change in elevation calculated as the final elevation minus the initial elevation.
1. **Change in elevation from –12 feet to 123 feet:**
\[
123 - (-12) = 123 + 12 = 135 \quad (\text{Positive change})
\]
2. **Change in elevation from 632 feet to 312 feet:**
\[
312 - 632 = -320 \quad (\text{Negative change})
\]
3. **Change in elevation from 492 feet to -783 feet:**
\[
-783 - 492 = -1275 \quad (\text{Negative change})
\]
4. **Change in elevation from sea level (0 feet) to -87 feet:**
\[
-87 - 0 = -87 \quad (\text{Negative change})
\]
Based on this assessment, the only situation that results in a positive change is:
- A change in elevation from –12 feet to 123 feet (135 feet positive change).
So, the correct response is the first one: a change in elevation from –12 feet to 123 feet.