A bridge is constructed across a river, and this shortens journey times. The table sets out the costs and benefits of constructing the bridge. private benefit = $12000$, private cost = $10000$, external benefit = $8000$, external cost = $5000$. Which calculation shows social benefit?
- A$12000 - 10000 = 2000$
- B$8000 - 5000 = 3000$
- C$12000 + 5000 = 17000$
- D$8000 + 12000 = 20000$