Final answer:
The correct answer is Duration.
Step-by-step explanation:
The rule of thumb in finance states that a bond's return should move about +/- 1% for each +/- 1% change in the yield per year of the duration of the bond.
The duration of a bond measures how sensitive its price is to changes in interest rates. A bond with a longer duration will experience a larger price change for a given change in interest rates compared to a bond with a shorter duration.
Therefore, the correct answer is c) Duration.