Why does immunization against interest rate shocks using duration for fixed$-$income securities work?

Question $5$ options:

$1)$

Because interest rate changes are relatively predictable.

$2)$

Because the gains or losses on reinvested cash flows that result from an interest rate change are exactly offset by losses or gains from the security when it is sold.

$3)$

Because the fixed$-$income security gravitates toward its maturity value as it approaches its maximum duration.

$4)$

Because cash flows that result from the security are not reinvested so they are not affected by interest rate changes in the same way as the security$\text{'}$s gain or loss when it is sold.

$5)$

It doesn't work because perfect immunization is impossible to accomplish.