The external accounts of the fictional economy of Norvale show the following balances for one year:
| Item | Balance |
|---|---|
| Trade in goods | -£82 billion |
| Trade in services | +£57 billion |
| Net secondary income | -£9 billion |
| Current account | -£46 billion |
What was Norvale's net primary income balance?
-£12 billion
+£12 billion
-£21 billion
-£34 billion