The concept of 'duration' in fixed income investing measures which of the following?

Duration is a measure of a fixed-income security's sensitivity to changes in interest rates. More precisely, modified duration estimates the percentage change in a bond's price for a 1% (100 basis points) change in yield. A bond with a duration of 5 years will approximately lose 5% of its price if interest rates rise by 1%. Duration is not simply the time to maturity it is a weighted average of the times at which the bond's cash flows are received, weighted by the present value of those cash flows. Zero-coupon bonds have the highest duration (equal to their maturity) because all cash flows occur at maturity. Bonds with higher coupons have lower duration because a greater proportion of cash flows are received earlier.